From the lists of Diogenes Laërtius, giving 227 titles, it appears that the activity of Theophrastus extended over the whole field of contemporary knowledge. His writing probably differed little from Aristotle's treatment of the same themes, though supplementary in details. Like Aristotle, most of his writings are lost works.
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 there is a certain plausibility to the well-known story that the works of Aristotle and Theophrastus were allowed to languish in the cellar of Neleus of Scepsis and his descendents.
On Plants
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 botany."
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:
to the reports of Alexander's followers he owed his accounts of such plants as the cotton-plant, banyan, pepper, cinnamon, myrrh and frankincense.
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.
The Characters
His book
The Characters, if it is indeed his, deserves a separate mention. The work contains thirty brief, vigorous and trenchant outlines of moral types, which form a most valuable picture of the life of his time, and in fact of human nature in general. They are the first recorded attempt at systematic character writing. The book has been regarded by some as an independent work; others incline to the view that the sketches were written from time to time by Theophrastus, and collected and edited after his death; others, again, regard the
Characters as part of a larger systematic work, but the style of the book is against this. Theophrastus has found many imitators in this kind of writing, notably Joseph Hall (1608), Sir Thomas Overbury (1614–16), Bishop Earle (1628) and Jean de La Bruyère (1688), who also translated the
Characters. George Eliot also took inspiration from Theophrastus' Characters, most notably in her book of caricatures,
Impressions of Theophrastus Such. Writing the "character sketch" as a scholastic exercise also originated in Theophrastus's typology.
On Sensation
A treatise
On Sense Perception and its objects is important for a knowledge of the doctrines of the more ancient Greek philosophers regarding the subject. A paraphrase and commentary on this work was written by Priscian of Lydia in the 6th century. With this type of work we may connect the fragments on
Smells, on
Fatigue, on
Dizziness, on
Sweat, on
Swooning, on
Palsy, and on
Honey.
Physics
We also possess in fragments a
History of Physics. To this class of work belong the still extant sections on
Fire, on the
Winds, and on the signs of
Waters,
Winds, and
Storms.Various smaller scientific fragments have been collected in the editions of Johann Gottlob Schneider (1818–21) and Friedrich Wimmer (1842...62) and in Hermann Usener's
Analecta Theophrastea.
Metaphysics
The Metaphysics (nine chapters) was considered a fragment of a larger work by Usener in his edition (Theophrastos
Metaphysica, Bonn, 1890) but according Ross and Fobes in their edition (Theophrastus
Metaphysica, Oxford, 1929) the treatise is complete (p. X) and this opinion is now widely accepted. There is no reason for assigning this work to some other author because it is not noticed in Hermippus and Andronicus, especially as Nicolaus of Damascus had already mentioned it.
On Stones
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.
