 Apart from these extant works, we know that Theophrastus wrote treatises on many more subjects in all areas of philosophy, but of those we have only their titles, some fragments, and few reports and paraphrases. The ancient authors who refer to Theophrastus’ writings are diverse and vary greatly in their reliability. For instance, traces of Theophrastus’ doctrines can be found in the works of Plutarch, Alexander of Aphrodisias, Galen, Sextus Empiricus, Diogenes Laertius, Pliny the Elder, Priscian, Simplicius, Themistius, Photius as well as in Arabic authors (Averroes, al-Fārābī, Ibn-an-Nadīm) and Latin sources (Albert the Great, Thomas Aquinas). The following list of titles of Theophrastus’ writings gives an idea of his prolific philosophical production: