The concept of mimēsis was ‘shared by most authors, philosophers and educated audiences in the classical period, in antiquity as a whole, and even later’, although it has probably never been developed into a well-articulated theory. As far as we can judge from the extant evidence, the meaning of the expressions μίμησις and μιμέομαι differs from author to author and sometimes even from passage to passage. Ancient Greek views on mimēsis have often been discussed in modern scholarship, mainly within the field of history of art, and it has been demonstrated repeatedly that the traditional English translation ‘imitation’ is not always appropriate for the ancient texts and that in many contexts it is rather misleading. In the following study I aim to focus on this concept as it was employed in the oldest Greek cosmological and philosophical theories. As a rule, the study of these theories is complicated by their fragmentary state of preservation and by their distortion through the specifically Platonic views that were dominant among the later doxographers. I shall suggest that the Platonizing tendency still prevalent today, which tends to translate and interpret mimēsis as ‘imitation’ or ‘copy’, should be carefully revised in the light of the Hippocratic evidence and specifically in view of De victu, probably the oldest authentic, non-fragmentary, and non-Platonic document attesting the concept of mimēsis.