A native of Eresos in Lesbos, he was Aristotle's close colleague and successor as head of the Lyceum, the Peripatetic school of philosophy in Athens.

Theophrastus wrote numerous treatises across all areas of philosophy, working to support, improve, expand, and develop the Aristotelian system.

Often considered the "father of botany" for his groundbreaking works "Enquiry into Plants" (Ancient Greek: Περὶ φυτῶν ἱστορία, romanized: Peri phytōn historia) and "On the Causes of Plants," (Ancient Greek: Περὶ αἰτιῶν φυτικῶν, romanized: Peri aitiōn phytikōn) Theophrastus established the foundations of botanical science.

His given name was Tyrtamos (Ancient Greek: Τύρταμος); the nickname Theophrastus ("divine speaker") was reputedly given to him by Aristotle in recognition of his eloquent style.

[6] His given name was Tyrtamus (Τύρταμος), but he later became known by the nickname "Theophrastus", given to him, it is said, by Aristotle to indicate the grace of his conversation (from Ancient Greek Θεός 'god' and φράζειν 'to phrase', i.e. divine expression).

[15] 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.

[25] Likewise, we find mention of monographs of Theophrastus on the early Greek philosophers Anaximenes, Anaxagoras, Empedocles, Archelaus,[26] Diogenes of Apollonia, Democritus,[27] which were made use of by Simplicius; and also on Xenocrates,[28] against the Academics,[29] and a sketch of the political doctrine of Plato.

[35] Besides these writings, Theophrastus wrote several collections of problems, out of which some things at least have passed into the Problems that have come down to us under the name of Aristotle,[36] and commentaries,[37] partly dialogue,[38] to which probably belonged the Erotikos (Ἐρωτικός),[39] Megacles (Μεγακλῆς),[28] Callisthenes (Καλλισθένης),[40] and Megarikos (Μεγαρικός),[23] and letters,[41] partly books on mathematical sciences and their history.

[5] 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 descendants.

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.

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.

[citation needed] A treatise On Sense Perception (Περὶ αἰσθήσεων) and its objects is important for a knowledge of the doctrines of the more ancient Greek philosophers regarding the subject.

[47] 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.

[11] The Metaphysics (anachronistic Greek title: Θεοφράστου τῶν μετὰ τὰ φυσικά),[48] in nine chapters (also known as On First Principles), was considered a fragment of a larger work by Usener in his edition (Theophrastos, Metaphysica, Bonn, 1890), but according to Ross and Fobes in their edition (Theophrastus, Metaphysica, Oxford, 1929), the treatise is complete (p. X) and this opinion is now widely accepted.

[43] In his treatise On Stones (Περὶ λίθων), which would become a source for other lapidaries until at least the Renaissance,[49] Theophrastus classified rocks and gems 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 deals with precious stones, emeralds, amethysts, onyx, jasper, etc., and describes a variety of "sapphire" that was blue with veins of gold, and thus was presumably lapis lazuli.

The ancient workings, consisting of shafts and galleries for excavating the ore, and washing tables for extracting the metal, may still be seen.

Although Pliny's treatment of the subject is more extensive, Theophrastus is more systematic and his work is comparatively free from fable and magic,[53] although he did describe lyngurium, a gemstone supposedly formed of the solidified urine of the lynx (the best ones coming from wild males), which featured in many lapidaries until it gradually disappeared from view in the 17th century.

[55] Lyngurium is described in the work of Theophrastus as being similar to amber, capable of attracting "straws and bits of wood", but without specifying any pyroelectric properties.

[56] The extent to which Theophrastus followed Aristotle's doctrines, or defined them more accurately, or conceived them in a different form, and what additional structures of thought he placed upon them, can only be partially determined because of the loss of so many of his writings.

[70] Closely connected with this treatise was that upon ambiguous words or ideas,[71] which, without doubt, corresponded to book Ε of Aristotle's Metaphysics.

[43] Theophrastus introduced his Physics with the proof that all natural existence, being corporeal and composite, requires principles,[72] and first and foremost, motion, as the basis of all change.

[73] 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.

Theophrastus seems, generally speaking, where the investigation overstepped the limits of experience, to have preferred to develop the difficulties rather than solve them, as is especially apparent in his Metaphysics.

[43] He was doubtful of Aristotle's teleology and recommended that such ideas be used with caution: With regard to the view that all things are for the sake of an end and nothing is in vain, the assignation of ends is in general not easy, as it is usually stated to be ... we must set certain limits to purposiveness and to the effort after the best, and not assert it to exist in all cases without qualification.He did not follow the incessant attempts by Aristotle to refer phenomena to their ultimate foundations, or his attempts to unfold the internal connections between the latter, and between them and phenomena.

[43] 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 (pneuma).

In later times, fault was found with his expression in the Callisthenes, "life is ruled by fortune, not wisdom" (vitam regit fortuna non sapientia).

[90] The marble herm figure with the bearded head of philosopher type, bearing the explicit inscription, must be taken as purely conventional.

André Thevet illustrated[93] in his iconographic compendium, Les vraies Pourtrats et vies des Hommes Illustres (Paris, 1584), an alleged portrait plagiarized from the bust, supporting his fraud with the invented tale that he had obtained it from the library of a Greek in Cyprus and that he had seen a confirming bust in the ruins of Antioch.