 Diels further argued that other reports, in other authors, should also be connected with Theophrastus’ foundational treatise. The passages dealing with the tenets of Presocratic philosophers in the history of philosophy by Diogenes Laërtius, which is arranged according to schools and individuals, not subjects, as well as similar sections of the first book of Hippolytus’ Refutation of All Heresies and of the Stromateis (‘Patchworks’) of another ps-Plutarch, in Diels’ view also went back, ultimately, to the Tenets of the Natural Philosophers. He failed to take the difference between treatment according to subject and that according to person, or school, sufficiently into account. His argumentation is also dubious in other respects. From the undeniable fact that there are striking resemblances between Theophrastus’ fragments concerned with the principles on the one hand, and what is found on that score in Aëtius, Diogenes Laërtius, and Hippolytus on the other, it does not follow that corresponding passages in these later authors for which we have no Theophrastean parallels derive from Theophrastus too. This is source criticism, or Quellenforschung, at its most vulnerable. Diels moreover preferred to overlook the equally undeniable fact that Aristotle’s treatment of the principles in the first book of the Metaphysics exhibits equally striking correspondences with Theophrastus’ fragments (Zeller 1877), and so with the later tradition as well, which could therefore go back ultimately to Aristotle, and not to Theophrastus.