=152.= But even if all ‘conceptions’ are ultimately derived from ‘perceptions,’ it does not follow that in each particular case the mind commences _de novo_ to collect and shape its material. On the contrary, it is clear that not only all practical life, but also all philosophy, takes for granted a great many matters which are either allowed by general consent, or at least assumed by the thinker; and these matters are mostly of the nature of class-conceptions. If it is stated that ‘the consul entered Rome in a chariot drawn by four horses,’ we assume that the ideas expressed by ‘consul,’ ‘chariot,’ ‘four,’ ‘horses,’ are matters of general consent, and we may go on to assume that the person of the consul and the locality called ‘Rome’ are also already known to the speaker and his hearers. The general term in the post-Aristotelian writers for such legitimate assumptions is ‘preconception’ (πρόληψις, _anticipatio_ or _praesumptio_). The precise meaning of this term (of which the invention is ascribed to Epicurus[57]) appears not to be always the same. Most commonly the ‘preconception’ is a general term or conception, and therefore to the Stoics it is one variety of the ἔννοια; it is ‘a mental shaping, in accordance with man’s nature, of things general’[58]. All such preconceptions are foreshadowings of truth, especially in so far as they correspond to the common judgment of mankind[59]; and the art of life consists in correctly applying these presumptions to the particular circumstances with which each individual man has to deal[60]. If the preconceptions are rightly applied, they become clearer by use, and thus attain the rank of true knowledge by a process of development or ‘unravelling’ (_enodatio_)[61]. As to the nature of a preconception, there is a great difference between Epicurus and the Stoics. Epicurus identifies all the terms ‘preconception,’ ‘comprehension,’ ‘right opinion,’ ‘conception,’ and ‘general notion,’ and maintains that each of these is nothing but memory of a sensation frequently repeated[62]; the Stoics however hold that preconceptions are established by the mind[63], and (so far as they are common to all men) by the universal reason. This difference is fundamental. Epicurus, as a materialist in the modern sense, explains perception as a bodily function, and ‘conceptions’ of every kind as mere echoes of such bodily functions. The Stoics on the other hand recognise at each stage the activity of mind, and this in increasing degree as we proceed to the higher levels of thought. [Sidenote: Notions of inner growth.]