No other meaning but this is to be found in the vaunted eternity of philosophy in regard to time and space. The eternity of every philosophic proposition must be affirmed against those who materialistically consider all propositions as valueless existences, and fugitives which leave no trace, as phenomena of brute matter, which alone persists. Philosophic propositions, though historically conditioned, are not effects produced and determined by these conditions, but creations of thought, which is continued in and through them. When they appear to be produced determinately, they must be held to be, not philosophy, but false philosophy, vital interests masquerading as thoughts. That alone can be eternal as philosophy, which is knowledge and truth. But when eternity is misunderstood as isolation from those conditions, it must then be denied, and in place of it the thesis of relativity must be admitted, provided we are careful that it does not assume the erroneous vesture of historical materialism and economic determinism. The thesis that the history of philosophy should be treated _psychologically,_ by the attribution of ideas to the temporal conditions and the personal experiences of philosophers, to social history and biography, is reducible (and it is worth while noticing this) to materialism and determinism in its least evident form, namely psychologism. Such a thesis is the failure to recognize spiritual value, or at least (as is the case with some unconscious æstheticists), the logical value of philosophy, whose history, when changed into that of the expressions of states of the soul, comes to coincide altogether with the history of poetry and literature. [Sidenote: _The concept of spontaneous, ingenuous, innate philosophy, etc., and its meaning._] The eternity of philosophy is its truth, and the conception which is sometimes brought forward of a _spontaneous_ or _ingenuous_ or _innate_ or _cryptic_ (_abdita_) philosophy, which alone should be permanent amid the variations of philosophic opinions, or to which the spirit should return after many wanderings, is nothing but a symbol of this truth. The Platonic theory of _reminiscence (anamneisis)_ is reducible to this conception. In this theory true knowledge is explained as the recollection of an original state; and it is this reminiscence, as the restitution of the childish soul, that is described by our Leopardi in the following verses: I believe that to know is very often, if we examine it, nothing but to perceive the folly of beliefs due to habit, and the careful reconquest of the knowledge of childhood, taken from us by age; for the child neither knows nor sees more than we, but he does not believe that he sees and knows.