[55] "Principles of Biology," vol. i, p. 74.
[56] _Ibid._
[57] Foster's "Physiology," p. 642.
[58] Op. cit., pp. 88, 89.
[59] "Natural Religion," p. 19.
[60] "Natural Religion," p. 20.
[61] Prof. Flint, "Theism," p. 805.
[62] Martineau. _Vide_ the whole Symposium on "The Influences upon Morality of a Decline in Religious Belief."--_Nineteenth Century_, vol. i. pp. 331, 531.
[63] Mueller: "Christian Doctrine of Sin." 2d Ed., vol i. p 131.
[64] It would not be difficult to show, were this the immediate subject, that it is not only a right but a duty to exercise the spiritual faculties, a duty demanded not by religion merely, but by science. Upon biological principles man owes his full development to himself, to nature, and to his fellow-men. Thus Mr. Herbert Spencer affirms, "The performance of every function is, in a sense, a moral obligation. It is usually thought that morality requires us only to restrain such vital activities as, in our present state, are often pushed to excess, or such as conflict with average welfare, special or general: but it also requires us to carry on these vital activities up to their normal limits. All the animal functions, in common with all the higher functions, have, as thus understood, their imperativeness."--"The Data of Ethics," 2d Ed., p. 76.