Looking to future generations, there is no cause to fear that the social instincts will grow weaker... the social instincts, - the prime principle of man's moral constitution - with the aid of active intellectual powers and the effects of habit, naturally lead to the golden rule, "As ye would that men should do to you; do ye to them likewise"; and this lies at the foundation of morality.

Often a cold shudder has run through me, and I have asked myself whether I may have not devoted myself to a fantasy.

We cannot fathom the marvelous complexity of an organic being; but on the hypothesis here advanced this complexity is much increased. Each living creature must be looked at as a microcosm--a little universe, formed of a host of self-propagating organisms, inconceivably minute and as numerous as the stars in heaven.

...I feel most deeply that the whole subject is too profound for the human intellect. A dog might as well speculate on the mind of Newton.— Let each man hope & believe what he can.—

The more one thinks, the more one feels the hopeless immensity of man's ignorance.

The several difficulties here discussed, namely our not finding in the successive formations infinitely numerous transitional links between the many species which now exist or have existed; the sudden manner in which whole groups of species appear in our European formations; the almost entire absence, as at present known, of fossiliferous formations beneath the Silurian strata, are all undoubtedly of the gravest nature.

I am quite conscious that my speculations run beyond the bounds of true science....It is a mere rag of an hypothesis with as many flaw[s] & holes as sound parts.