=Disbelief in the "monumentum aere perennius".=[13]--A decided disadvantage, attending the termination of metaphysical modes of thought, is that the individual fixes his mind too attentively upon his own brief lifetime and feels no strong inducement to aid in the foundation of institutions capable of enduring for centuries: he wishes himself to gather the fruit from the tree that he plants and consequently he no longer plants those trees which require centuries of constant cultivation and are destined to afford shade to generation after generation in the future. For metaphysical views inspire the belief that in them is afforded the final sure foundation upon which henceforth the whole future of mankind may rest and be built up: the individual promotes his own salvation; when, for example, he builds a church or a monastery he is of opinion that he is doing something for the salvation of his immortal soul:--Can science, as well, inspire such faith in the efficacy of her results? In actual fact, science requires doubt and distrust as her surest auxiliaries; nevertheless, the sum of the irresistible (that is all the onslaughts of skepticism, all the disintegrating effects of surviving truths) can easily become so great (as, for instance, in the case of hygienic science) as to inspire the determination to build "eternal" works upon it. At present the contrast between our excitated ephemeral existence and the tranquil repose of metaphysical epochs is too great because both are as yet in too close juxtaposition. The individual man himself now goes through too many stages of inner and outer evolution for him to venture to make a plan even for his life time alone. A perfectly modern man, indeed, who wants to build himself a house feels as if he were walling himself up alive in a mausoleum. [13] Monument more enduring than brass: Horace, Odes III:XXX. 23