In the description in the Book of Exodus, manna is described as appearing each morning after the dew had gone, while in the description in the Book of Numbers, manna arrived with the dew during the night; the Book of Exodus adds that manna was comparable to hoarfrost in size, and similarly had to be collected before it was melted by the heat of the sun. According to the Biblical description, manna resembled coriander seed; in the Book of Exodus, manna is described as being white in colour, while the Book of Numbers describes it as being the same colour as bdellium. According to the Book of Numbers, the Israelites ground it up and pounded it into cakes, which were then baked, resulting in something that tasted like olive oil; the Book of Exodus states that it tasted like wafers that had been made with honey. The Israelites were instructed to only eat the manna they had gathered for each day, for leftovers or storing any up for the following day resulted in manna that "bred worms and stank". The exception to this occurrence was the day before the Sabbath when twice the amount of manna was gathered, which did not spoil overnight.
Textual scholars view the two descriptions of manna as deriving from different sources, with the description in the Book of Numbers being from the Jahwist text, and the description in the Book of Exodus being from the later Priestly Source. The Babylonian Talmud, however, argues instead that the differences in description were due to the taste varying depending on who ate it, with it tasting like honey for small children, like bread for youths, and like oil for the elderly; similarly classical rabbinical literature rectifies the question of whether manna came before or after dew, by arguing that the manna was sandwiched between two layers of dew, one layer of dew falling before the manna, and the other falling after it.
Some scholars have proposed that manna is cognate with the Egyptian term mennu, meaning food. At the turn of the 20th century, Arabs residing in the Sinai Peninsula were selling resin from the tamarisk tree as man es-simma, roughly meaning heavenly manna. Tamarisk trees (particularly Tamarix Gallica) were once comparatively extensive throughout the southern parts of the Sinai Peninsula, and their resin is similar to wax, melts in the sun, is sweet and aromatic (like honey), and has a dirty-yellow colour, fitting somewhat with the biblical descriptions of manna; however, this resin is mostly composed from sugar, so it couldn't provide sufficient nutrition for a population to survive over large periods of time, and it would be very difficult for it to have been compacted to become cakes.
In the Biblical account, the name manna is said to derive from the question man hu, seemingly meaning what is this?; but this is an Aramaic etymology not a Hebrew one. Man here is most likely to be cognate with the Arabic term man, meaning plant lice, with man hu thus meaning this is plant lice; the equation with plant lice fits with one of the two most widespread modern identifications of manna, namely that manna refers to the crystallised honeydew of certain scale insects. In the environment of a desert, such honeydew rapidly dries due to evaporation of its water content, becoming a sticky solid, and later turning whitish, yellowish, or brownish; honeydew of this form is considered a delicacy in the middle east, and is a good source of carbohydrate.
The other widespread identification is that manna is the thalli of certain Lichen (particularly Lecanora esculenta); this food source is often used as a substitute for maize in the steppes of central asia. This material is light, often drifting in the wind, and has a yellow outer coat with white inside, somewhat matching the biblical description of manna, although it does need additional drying, and is definitely not similar to honey in taste.
A number of ethnomycologists such as R. Gordon Wasson, John Marco Allegro and Terence McKenna, have rediscovered that most of characteristics of manna are similar to that of psilocybe cubensis, namely that such mushrooms are notorious breeding grounds for insects and decompose rapidly. These peculiar fungi which naturally produce a number of molecules which resemble human neurochemicals first appear as small fibres (called mycellium) which resemble hoarfrost. This speculation (also paralleled in Philip K. Dick's posthumously published The Transmigration of Timothy Archer) is supported in a wider cultural context when compared with the praise of Haoma in the Rigveda, and Mexican praise of teonanácatl as well as the peyote sacrament of the Native American Church, and the Holy Ayahuasca used in the ritual of the Unaio De Vegital. However, though perhaps due to prohibition-related stigma, many resist the idea that the Holy Sacrament could be psychoactive (as wine is).
Viewed by scholars as most implausible is the hypothesis of Immanuel Velikovsky that manna consisted of hydrocarbon rain resulting from a close encounter between Venus and Earth; this claim has been debunked by Carl Sagan, Stephen Jay Gould, and others.
Other minority identifications of manna are that it was a kosher species of locust, that it was the sap of certain succulent plants (such as those of the genus Alhagi, which have an appetite-suppressing effect), or that it was the miraculous appearance of fully-formed wafers of shewbread. Some people also attribute it to the hemp seed.
The origin of Manna is clearly in heaven according to the Bible (Psalms 78:24,25, Psalm 105:40 and John 6:31), but the various naturalistic identifications of manna have been compared to things in nature. In the Mishnah manna is treated as a supernatural substance, created during the twilight of the first Friday in existence, and ensured to be clean by the sweeping of the ground by a northern wind, and subsequent rains, before it arrives. According to classical rabbinical literature, manna was ground in a heavenly mill for the use of the righteous, but some of it was allocated to the wicked and left for them to grind themselves.
As a natural food substance, the consumption of manna would produce waste products; but in classical rabbinical literature, as a supernatural substance, it was argued that manna produced no waste, resulting in no defecation among the Israelites until several decades later, when the manna had ceased to fall. According to modern medical science, the lack of defecation over such a long period of time would cause extremely severe bowel problems, especially when other food later began to be consumed again; the classical rabbinical writers argue that the Israelites complained about the lack of defecation, and were concerned about potential bowel problems.
According to a number of vegetarian Christians, God had originally intended that man would not eat meat, because (according to these sources) plants cannot move, and therefore killing them wouldn't be sinful; the supply of manna, a non-meat substance, is quoted by these sources as an example of this intention against eating meat. This may perhaps be reinforced in that when the people complained and wished for quail, God gave it to them, and those who ate it grew sick after.
Food wasn't the only use that manna was put to, according to the rabbinical writers; one classical rabbinical source states that the fragrant odour of manna was used as a perfume by the Israelite women.
According to the biblical text, each day exactly one Omer of manna was gathered per member of each household, regardless of how much effort was put into gathering it; a midrash attributed to Rabbi Tanhuma remarks that although some people were diligent enough to go into the fields to gather manna, lazy individuals just lay down and caught it with their outstretched hands. The Talmud argues that this property was used to solve disputes about the ownership of slaves, since the number of omers of manna each household could gather would indicate how many people were legitimately part of the household; the omers of manna for stolen slaves could only be gathered by the legitimate owner, and therefore the legitimate owner would have a spare omer of manna.
Nevertheless, according to the Talmud, manna was found near to the homes of those with strong belief in Yahweh, and far from the homes of those with doubts; indeed, one classical midrash argues that manna was intangible to non-Jews, as it would inevitably slip from their hands. The Midrash Tanhuma argues that when manna melted, it formed liquid streams that were drunk by a number of animals, flavouring their flesh; this Midrash goes on to argue that some of these animals were subsequently eaten by non-Israelites (implying that such food was also available as an alternative to manna), and it was only in this indirect manner that non-Israelites were able to taste manna. Despite these descriptions of uneven distribution, classical rabbinical literature expresses the view that the manna fell in very large quantities each day, layering over two thousand square cubits, between 50-60 cubits in height; rabbinical literature states that this was enough to nourish the Israelites for 2000 years, and could be seen from the palaces of every king in the East and West, although this improbable statement may be metaphorical.
The biblical text states that twice as much manna than usual was available on Friday mornings, and none at all could be found on the following day; the text goes on to state that although the manna usually rotted after a single night, the manna which had been collected on Fridays remained fresh for two nights. According to the narrative, the Sabbath was instituted at this point, with Moses stating that the extra portion was to be consumed on the Sabbath, and Yahweh instructing him that no one should leave his place on the Sabbath, so that the people could rest during it.
Textual scholars regard this part of the manna narrative to be spliced together from the Yahwist and Priestly Source texts, with the Yahwist text being the one emphasising rest during the sabbath, while the Priestly Source merely states that a sabbath exists, implying that the meaning of a sabbath was already known. Biblical scholars regard this part of the manna narrative as an aetiological myth designed to explain the origin of sabbath observance, which in reality was probably pre-Mosaic.
According to the Book of Exodus, the Israelites consumed the manna for 40 years, but it then ceased to appear once they had reached a settled land; the Book of Exodus also states that the manna ceased to appear once the Israelites reached the borders of Canaan (which was inhabited, by the Canaanites). According to the Book of Joshua, the manna ceased to appear on the day after the annual passover festival, when the Israelites had reached Gilgal. Textual scholars attribute these variations to the fact that each expression, of when the manna ceased, derives from different source texts; the claim that the Israelites ate manna for 40 years, until reaching a settled land, is attributed by textual scholars to the Priestly Source; the reference to Canaan's borders is considered to be either from the Jahwist account, or a later redaction to synchronise the account with that of the book of Joshua. There is also a disagreement among classical rabbinical writers as to when the manna ceased, particularly in regard to whether it remained after the death of Moses for a further 40 days, 70 days, or 14 years; indeed, according to Joshua ben Levi, the manna ceased to appear at the moment that Moses died.
Despite the eventual termination of the supply of manna, the text states that a small amount of it survived within a pot, which was kept adjacent to the Ark of the Covenant; the text indicates that the instruction for this to occur had been given to Moses by Yahweh, and Moses had delegated the task to Aaron. The Epistle to the Hebrews gives a slightly different account, stating that the pot was stored inside the Ark. The classical rabbinical sources give different viewpoints on how long the pot survived, with some arguing that it was only there for the generation following Moses, and others arguing that it survived at least until the time of Jeremiah; textual scholars attribute the mention of the pot to the priestly source, therefore indicating that the pot existed in the early 6th century BC.
By extension "manna" has been used to refer to any divine or spiritual nourishment. In a modern botanical context, manna is often used to refer to the secretions of various plants, especially of certain shrubs and trees, and in particular the sugars obtained by evaporating the sap of the Manna Ash, extracted by making small cuts in the bark. The Manna Ash, native to southern Europe and southwest Asia, produces a blue-green sap, which has medicinal value as a mild laxative, demulcent, and weak expectorant.
In the 17th century, a woman manufactured a clear, tasteless, cosmetic product, which she named the Manna of Saint Nicholas of Bari; initially this was very popular, but after the deaths of 600 men, who were married to women using the product, government investigations discovered that the cosmetic was primarily composed of arsenic. In modern times, Roman Catholic authorities annually collect a clear liquid from the tomb of Saint Nicholas; the pleasant perfume of this liquid is argued by Roman Catholic legend to be able to ward off evil, and for this reason it is sold to pilgrims as the Manna of Saint Nicholas. The liquid gradually seeps out of the tomb, but it is unclear whether it originates in the body within the tomb, or from the marble itself; since the town of Bari is a harbour, and the tomb is below sea level, there are several natural explanations for the Manna fluid, including the transfer of seawater to the tomb by capillary action.