See his memoirs (1968).
This cookbook, first printed in 1669, is an excellent resource of the types of food that were eaten by persons of means in the early 1600's. It is supposedly based upon writings of Sir Kenelm Digby, a privateer whose interests, apparently, included cooking, medicine, swordplay, astrology, alchemy, literature, and natural philosophy. The introduction to his cookbook, written by Anne Macdonell for a reprint in 1910, includes many interesting tidbits about the author.
The complete title of his book is "THE CLOSET Of the Eminently Learned Sir Kenelm Digbie Kt. OPENED: Whereby is DISCOVERED Several ways for making of Metheglin, Sider, Cherry-Wine &c. TOGETHER WITH Excellent Directions FOR COOKERY: as also for Preserving, Conserving, Candying, &c." (The eccentric capitalization is from the book, and is not the conceit of the author of this page.) This, however, is a bit wordy for common use; most scholars refer to it as "Kenelm Digby's Closet," or, if speaking solely about cookbooks, merely, "Digby."
This, and other works, according to Anne Macdonell, was not intended, by the author, for publication, but for his own use. They were published by the efforts of others, notably his steward, Hartman, and his son, John, who experienced some financial difficulty after his father's death.
Like most historical cookbooks, however, it does not include complete information on the preparation of the foods within; while methods of cooking and ingredients are included, amounts are, by and large, not. This is standard for cookbooks and herbals of this time, and earlier, and requires some experimentation.
Modern scholars who work with medieval and ancient cookbooks must engage in the process of redaction to duplicate the dishes within; for cookbooks, redaction means a formulation, based upon trial-and-error, of a (hopefully, edible) dish which uses the ingredients and methods in the book. These recipes, with baking times, amounts, and any additional information, are called "redactions," being more than merely translations.
Digby, for its type, includes a great deal of information, and rather bridges the period between the era of the Renaissance and the medieval period; it includes suggested uses of the recipes, as, in ancient and medieval times, foods were considered also curative, and the difference between a cookbook and an herbal or medical text, was slight, even non-existent.
Unlike many antique cookbooks, Digby includes a vast array of ingredients, including flowers, vegetables, meats, herbs, spices, alcohol, fruits and berries, eggs, milk, grains, and honey. In fact, his recipes include substitutions, based, we can assume, on both personal taste, and seasonal availability.
This variety should give those engaged in historical reenactment enough options that they can both provide authentic foods, and, perhaps, extrapolate a bit on variations.
A great deal of the work appears to be taken up with various mead and metheglin recipes, but there are plenty of other recipes for sallets (which we would, today, call salads), eggs, several recipes for types of potage, recipes for meat pie and meat and vegetable pasty, cooked and prepared meats, syllabub, cakes, dessert pies, jellies and puddings and other sweets and desserts. There are also some other recipes that fall into other headings; for information, please read the book, online.