Theophrastus (Greek: Θεόφραστος; 371 – c. 287 BC), a Greek native of Eressos in Lesbos, was the successor of Aristotle in the Peripatetic school. His interests were wide-ranging, extending from biology and physics to ethics and metaphysics. His two surviving botanical works, Enquiry into Plants and On the Causes of Plants, were an important influence on medieval science. There are also surviving works On Moral Characters, On Sensation, On Stones, and fragments on Physics and Metaphysics all written in Greek. In philosophy, he studied grammar and language, and continued Aristotle's work on logic. He also regarded space as the mere arrangement and position of bodies, time as an accident of motion, and motion as a necessary consequence of all activity. In ethics, he regarded happiness as depending on external influences as well as on virtue, and famously said that "life is ruled by fortune, not wisdom." He succeeded Aristotle at the Lyceum.
According to some sources, Theophrastus' father was named Messapus, and was married to a woman named Argiope and was the father of Cercyon -- but, this is not certain.
After receiving his first introduction to philosophy in Lesbos from one Leucippus or Alcippus, he proceeded to Athens, and became a member of the Platonist circle. After Plato's death he attached himself to Aristotle, and in all probability accompanied him to Stagira. The intimate friendship of Theophrastus with Callisthenes, the fellow-pupil of Alexander the Great, the mention made in his will of an estate belonging to him at Stagira, and the repeated notices of the town and its museum in the nine books of his Enquiry into plants and his six books of Causes of Plants point to this conclusion.
Aristotle in his will made him guardian of his children, including Nicomachus with whom he was close. Aristotle likewise bequeathed to him his library and the originals of his works, and designated him as his successor at the Lyceum on his own removal to Chalcis. Eudemus of Rhodes also had some claims to this position, and Aristoxenus is said to have resented Aristotle's choice.
Theophrastus presided over the Peripatetic school for thirty-five years, and died at the age of eighty-five according to Diogenes. He is said to have remarked "we die just when we are beginning to live".
Under his guidance the school flourished greatly— there were at one period more than 2000 students, Diogenes affirms, and at his death, according to the terms of his will preserved by Diogenes, he bequeathed to it his garden with house and colonnades as a permanent seat of instruction. The comic poet Menander was among his pupils. His popularity was shown in the regard paid to him by Philip, Cassander and Ptolemy, and by the complete failure of a charge of impiety brought against him. He was honoured with a public funeral, and "the whole population of Athens, honouring him greatly, followed him to the grave. He was succeeded as head of the Lyceum by Strato of Lampsacus.
Thus Theophrastus, like Aristotle, had composed a first and second Analytic. He had also written books on Topics; on the refutation of fallacies; as well as books on the Principles of Natural Philosophy (Physica Auscultatio), on Heaven, and on Meteorological Phenomena. The work of Theophrastus On Affirmation and Denial seems to have corresponded to that of Aristotle's On Judgment.
In addition, he wrote on the Warm and the Cold, on Water, Fire, the Sea, on Coagulation and Melting, on various phenomena of organic and spiritual life, and on the Soul and Sensuous Perception. Likewise we find mention of monographs of Theophrastus on the early Greek philosophers Anaximenes, Anaxagoras, Empedocles, Archelaus, Diogenes of Apollonia, Democritus, which were made use of by Simplicius; and also on Xenocrates, against the Academics, and a sketch of the political doctrine of Plato. That he studied general history, as we see from the quotations in Plutarch's lives of Lycurgus, Solon, Aristides, Pericles, Nicias, Alcibiades, Lysander, Agesilaus, and Demosthenes, which were probably borrowed from the work on Lives. But his main efforts were to continue the labours of Aristotle in Natural History. This is testified not only by a number of treatises on individual subjects of zoology, of which, besides the titles, only fragments remain, but also by his books on Stones, his Enquiry into Plants, and On the Causes of Plants, which have come down to us entire. In politics, also, he seems to have trodden in the footsteps of Aristotle. Besides his books on the State, we find quoted various treatises on Education, on Royalty, on the Best State, on Political Morals, and particularly his works on the Laws, one of which, containing a recapitulation of the laws of various barbarian as well as Greek states, was intended to be a companion to Aristotle's outline of Politics, and must have been similar to it. He also wrote on oratory and poetry. Theophrastus, without doubt, departed further from Aristotle in his ethical writings, as also in his metaphysical investigations respecting motion, the soul, and God.
Besides these writings, Theophrastus was the author of several collections of problems, out of which some things at least have passed into the Problems which have come down to us under the name of Aristotle, and commentaries, partly dialogues, to which probably belonged the Erotikos, Megacles, Callisthenes, and Megarikos, and letters, partly books on mathematical sciences and their history.
Many of his works which we do have, exist only in fragmentary form. "The style of these works, as of the botanical books, suggests that, as in the case of Aristotle, what we possess consists of notes for lectures or notes taken of lectures," his translator Arthur Hort remarks. "There is no literary charm; the sentences are mostly compressed and highly elliptical, to the point sometimes of obscurity." The text of these fragments and extracts is often so corrupt that the well-known story of the fate of the books of Aristotle and Theophrastus (see Apellicon) might very well be true.
The most important of his books are two large botanical treatises, Enquiry into Plants, and On the Causes of Plants, which constitute the most important contribution to botanical science during antiquity and the Middle Ages, the first systemization of the botanical world; on the strength of these works some call him the "father of Taxonomy".
The Enquiry into Plants was originally ten books, of which nine survive. The work is arranged into a system whereby plants are classified according to their modes of generation, their localities, their sizes, and according to their practical uses such as foods, juices, herbs, etc. The first book deals with the parts of plants; the second book with the reproduction of plants and the times and manner of sowing; the third, fourth and fifth books are devoted to trees, their types, their locations, and their practical applications; the sixth book deals with shrubs and spiny plants; the seventh book deals with herbs; the eighth book deals with plants which produce edible seeds; and the ninth book deals with plants which produce useful juices, gums, resins, etc.
On the Causes of Plants was originally eight books, of which six survive. It concerns the growth of plants; the influences on their fecundity; the proper times they should be sown and reaped; the methods of preparing the soil, manuring it, and the use of tools; of the smells, tastes, and properties of many types of plants. The work deals mainly with the economical uses of plants rather than their medicinal uses, although the latter is sometimes mentioned.
Although these works contain many absurd and fabulous statements, as a whole they have many valuable observations concerning the functions and properties of plants. Theophrastus detected the process of germination and realized the importance of climate and soil to plants. Much of the information on the Greek plants may have come from his own observations, as he is known to have travelled throughout Greece, and to have had a botanical garden of his own; but the works also profit from the reports on plants of Asia brought back from those who followed Alexander the Great:
Theophrastus' Enquiry into Plants was first published in a Latin translation by Theodore Gaza, at Treviso, 1483; in its original Greek it first appeared from the press of Aldus Manutius at Venice, 1495-98, from a third-rate manuscript, which, like the majority of the manuscripts that were sent to printers' workshops in the fifteenth and sixteenth century, has disappeared. Wimmer identified two manuscripts of first quality, the Codex Urbinas in the Vatican Library, which was not made known to J.G. Schneider, who made the first modern critical edition, 1818-21, and the excerpts in the Codex Parisiensis in the Bibliothèque nationale de France.
We possess a treatise On Stones, in which Theophrastus classified rocks based on their behavior when heated, further grouping minerals by common properties, such as amber and magnetite which both have the power of attraction. He also comments on the effect of heat on minerals, and their different hardnesses.
He describes different marbles; mentions coal, which he says is used for heating by metal-workers; describes the various metal ores; and knew that pumice-stones had a volcanic origin. He also deals with precious stones, emeralds, amethysts, onyx, jasper, etc., and describes a variety of "sapphire" which was blue with veins of gold, and thus was presumably lapis-lazuli.
He knew that pearls came from shell-fish, that coral came from India and speaks of the fossilized remains of organic life. Theophrastus made the first known reference to the phenomenon of pyroelectricity, noting that the mineral tourmaline becomes charged when heated. He also considers the practical uses of various stones, such as the minerals necessary for the manufacture of glass; for the production of various pigments of paint such as ochre; and for the manufacture of plaster. He discusses the use of the touchstone for assaying gold and gold alloys, an important property which would require the genius of Archimedes to resolve in quantitative detail when he was asked to investigate the suspected debasement of a crown a few years later.
Many of the rarer minerals were found in mines, and he mentions the famous copper mines of Cyprus and the even more famous silver mines, presumably of Laurium near Athens, and upon which the wealth of the city was based, as well as referring to gold mines. The Laurium silver mines, which were the property of the state, were usually leased for a fixed sum and a percentage on the working. Towards the end of the 5th century the output fell, partly owing to the Spartan occupation of Decelea. But the mines continued to be worked, though Strabo records that in his time the tailings were being worked over, and Pausanias speaks of the mines as a thing of the past. The ancient workings, consisting of shafts and galleries for excavating the ore, and washing tables for extracting the metal, may still be seen. Theophrastus wrote a separate work On Mining, which like most of his writings is a lost work.
Pliny the Elder makes clear references to his use of On Stones in his Naturalis Historia of 77 AD, while updating and making much new information available on minerals himself. Although Pliny's treatment of the subject is more extensive, Theophrastus is more systematic and his work is comparatively free from fable and magic. From both these early texts was to emerge the science of mineralogy, and ultimately geology. Pliny is especially observant on crystal habit and mineral hardness for example.
Concerning judgment, he wrote at length on its unity, on the different kinds of negation, and on the difference between unconditional and conditional necessity. In his doctrine of syllogisms he brought forward the proof for the conversion of universal affirmative judgments, differed from Aristotle here and there in the laying down and arranging the modi of the syllogisms, partly in the proof of them, partly in the doctrine of mixture, i.e. of the influence of the modality of the premises upon the modality of the conclusion. Then in two separate works he dealt with the reduction of arguments to the syllogistic form and on the resolution of them; and further, with hypothetical conclusions. For the doctrine of proof, Galen quotes the second Analytic of Theophrastus, in conjunction with that of Aristotle, as the best treatises on that doctrine. In different monographs he seems to have tried to expand it into a general theory of science. To this too may have belonged the proposition quoted from his Topics, that the principles of opposites are themselves opposed, and cannot be deduced from one and the same higher genus. For the rest, some minor deviations from the Aristotelian definitions are quoted from the Topica of Theophrastus. Closely connected with this treatise was that upon ambiguous words or ideas, which, without doubt, corresponded to book E of Aristotle's Metaphysics.
Theophrastus introduced his Physics with the proof that all natural existence, being corporeal and composite, requires principles, and first and foremost, motion, as the basis of all change. Denying the substance of space, he seems to have regarded it, in opposition to Aristotle, as the mere arrangement and position (taxis and thesis) of bodies. Time he called an accident of motion, without, it seems, viewing it, with Aristotle, as the numerical determinant of motion.
He departed more widely from Aristotle in his doctrine of motion, since on the one hand he extended it over all categories, and did not limit it to those laid down by Aristotle; and on the other hand, while he viewed motion, with Aristotle, as an activity, not carrying its own goal in itself (ateles), of that which only potentially exists, and therefore could not allow that the activity expended itself in motion, he also recognised no activity without motion, and so referred all activities of the soul to motion: the desires and emotions to corporeal motion, judgment (kriseis) and contemplation to spiritual motion. The idea of a spirit entirely independent of organic activity, must therefore have appeared to him very doubtful; yet he appears to have contented himself with developing his doubts and difficulties on the point, without positively rejecting it. Other Peripatetics, like Dicaearchus, Aristoxenus, and especially Strato, developed further this sensualism in the Aristotelian doctrine.
Theophrastus seems, generally speaking, where the investigation overstepped the limits of experience, to have shown more acuteness in the development of difficulties than in the solution of them, as is especially apparent in the fragment of his Metaphysics. In a penetrating and unbiased conception of phenomena, in acuteness of reflection and combination respecting them and within their limits, in compass and certainty of experimental knowledge, he may have stood near Aristotle, if he did not come quite up to him: the incessant endeavour of his great master to refer phenomena to their ultimate foundations, his greater insight in unfolding the internal connections between the latter, and between them and phenomena, were not possessed by Theophrastus. Hence even in antiquity it was a subject of complaint that Theophrastus had not expressed himself with precision and consistency respecting God, and had understood it at one time as Heaven, at another an (enlivening) breath (pnemua).
Theophrastus was opposed to eating meat on the grounds that it robbed animals of life and was therefore unjust. Non-human animals, he said, can reason, sense, and feel just as human beings do. In this he was strongly opposed to Aristotle's argument that non-human animals ranked far below humans in the Great Chain of Being, and that they had no interests of their own.