In the desire after immortality also, the influence of the principle of summation is manifest. Thus Helmholtz, (_über die Entstehung des Planetensystems_, lecture delivered at Heidelberg and Cologne, 1871), in seeking to offer a hopeful prospect to those who cherish this desire, says: “The individual (if that which we achieve can ennoble the lives of those who succeed us) may face fearlessly the thought that the thread of his own consciousness will one day be broken. But to the thought of a final annihilation of the race of living mortals, and with them, the fruits of the striving of all past generations, even men of minds so unfettered and great as Lessing and David Strauss could scarcely reconcile themselves.” When it is scientifically shown that the earth will one day be incapable of supporting living beings, then, he thinks, the need of immortality will irresistibly return, and we shall feel bound to cast about for something which will afford us the possibility of assuming it. [67] (_p. 34_). _Metaph._ Δ 10. [68] (_p. 37_). This is the standing doctrine of the great theologians, as e.g. Thomas Aquinas in his _Summa Theologica_. Only certain nominalists, like Robert Holcot, teach the complete arbitrariness of the divine commands. Cf. my essay on the _Geschichte der kirchlichen Wissenschaften im Mittelalter_, in Möhler’s _Church History_ (published by Gams, 1867) vol. ii. 526 seq., respecting which, however, the reader is asked not to overlook the revision of the printer’s errors in the “errata,” p. 103 seq., at the end of that work. [69] (_p. 39_). At a time when psychology was far less advanced and inquiries into the province of the calculation of probability had not brought sufficient clearness into the process of rational induction, it was possible even for a Hume to fall a victim to this gross confusion. Cf. his _Enq. concern. Hum. Underst._, chaps. v. and vi. More striking is it that James Mill and Herbert Spencer have still not advanced in the slightest degree beyond Hume; (Cf. _Anal. of the Phen. of the Hum. Mind_, vol. ii. chap. ix. and note 108), and that even the acute thinker, J. S. Mill, although Laplace’s _Essai Philosophique sur les Probabilités_ lay at his disposal, never arrived at a clear distinction of the essential difference between these two forms of procedure. This hangs together with his failure to appreciate the purely analytic character of mathematics and the import of the deductive procedure in general. Indeed he has absolutely denied that the syllogism leads to new knowledge. Whoever bases the whole of mathematics upon induction cannot possibly justify mathematically the inductive procedure. It would be for him a _circulus vitiosus_. It is here beyond question that Jevon’s _Logic_ takes a truer view.