Sextus Empiricus Pyrrhoniae Hypotyposes 2.14.199

[199] If, then, one has to apprehend beforehand that when there is day there certainly is light also, in order to construct the hypothetical premiss ‟If it is day, it is light,” while by means of this premiss we deduce that when it is day it is light, the co-existence of the being of day and of night being proved (so far as depends on the axiomatic argument before us) by the premiss ‟If it is day, it is light,” and that premiss in turn being established by the co-existence of the facts aforesaid, —in this case also the fallacy of circular reasoning overthrows the substance of the argument.