 The titles of Theophrastus’ zoological treatises, as well as our testimonies with regard to his research in this area, suggest that he did not pursue Aristotle’s interest in the anatomical structure of living creatures, but tried to supplement the Aristotelian approach with observations on animal behaviour and its causes. The variations in animals resulting from different local environments, the generation of swarming creatures and the nuisance caused by them, the psychological qualities shared by animals with humans, and hibernation and reproduction, are some of the themes in Theophrastus’ zoological works that our secondary sources discuss (frs. 350–383 FHS&amp;G). Some of these Theophrastus introduced as strange and paradoxical, for some he offered multiple explanations, in some cases he simply repeated the Aristotelian view, in others it is disputable whether or not his account differed considerably from Aristotle’s. For instance, in the case of spontaneous reproduction (frs. 376–383 FHS&amp;G), some scholars have claimed that Theophrastus shared Aristotle’s views, while others have insisted that he is certainly more sceptical than Aristotle. It has also been suggested that Theophrastus agreed with the Aristotelian doctrine in the Metaphysics (Ζ 7 1032a30), according to which the same plants and animals can come either from seed or spontaneously, but not with Aristotle’s view in his biology that there is a sharp distinction between the plants and animals that are generated from inanimate matter and those that never are (e.g., On the Generation of Animals 1.1 715b8–15); in fact, this suggestion has been presented as evidence in favour of the thesis that some of Theophrastus’ zoological works may have been written before Aristotle’s biological treatises (see Balme 1962).