truly represent that existent thing.  Aug. Cont.  Acad. II. 11 quotes Cicero’s definition and condenses it thus; his signis verum posse comprehendi quae signa non potest habere quod falsum est. Iudicium:  [Greek:  kriterion], a test to distinguish between the unknown and the known. Eo, quo minime volt:  several things are clear, (1) that Philo headed a reaction towards dogmatism, (2) that he based the possibility of knowledge on a ground quite different from the [Greek:  kataleptike phantasia], which he pronounced impossible, (3) that he distorted the views of Carneades to suit his own.  As to (1) all ancient testimony is clear, cf. 11, Sextus Pyrr.  Hyp. I. 235, who tells us that while the Carneadeans believed all things to be [Greek:  akatalepta], Philo held them to be [Greek:  katalepta], and Numenius in Euseb. Praep.  Ev. XIV. 8, p. 739, who treats him throughout his notice as a renegade. (2) is evident from the Academica and from Sextus as quoted above.  The foundation for knowledge which he substituted is more difficult to comprehend.  Sextus indeed tells us that he held things to be in their own nature [Greek:  katalepta (hoson de epi te physei ton pragmaton auton katal.)].  But Arcesilas and Carneades would not have attempted to disprove this; they never tried to show that things in themselves were incognisable, but that human faculties do not avail to give information about them.  Unless therefore Philo deluded himself with words, there was nothing new to him about such a doctrine.  The Stoics by their [Greek:  kataleptike phantasia] professed to be able to get at the thing in itself, in its real being, if then Philo did away with the [Greek:  katal. phant.] and substituted no other mode of curing the defects alleged by Arcesilas and Carneades to reside in sense, he was fairly open to the retort of Antiochus given in the text.  Numenius treats his polemic against the [Greek:  katal. phant.] as a mere feint intended to cover his retreat towards dogmatism.  A glimpse of his position is afforded in 112 of this book, where we may suppose Cic. to be expressing the views of Philo, and not those of Clitomachus as he usually does.  It would seem from that passage that he defined the cognisable to be “quod impressum esset e vero” ([Greek:  phantasia apo hyparchontos enapomemagmene]), refusing to add “quo modo imprimi non posset a falso ([Greek:  hoia ouk an genoito apo me hyparchontos]), cf. my n. on the passage.  Thus defined, he most likely tried to show that the cognisable was equivalent to the [Greek:  delon] or [Greek:  pithanon] of Carneades, hence he eagerly pressed the doubtful statement of the latter that the wise man would “opine,” that is, would pronounce definite judgments on phenomena. (See 78 of this book.) The scarcity of references to Philo in ancient authorities does not allow of a more exact view of his doctrine.  Modern inquiry has been able to add little or nothing