lished between the expert and the public, and the slow and natural process of leavening the social lump by discovery and discussion will be displaced by something far less safe and salutary. On this count, then, I claim acquittal, being for the moment on the side of Virchow.
In a discourse delivered before the British Association at Liverpool, after speaking of the theory of evolution applied to the primitive condition of matter as belonging to "the dim twilight of conjecture," and affirming that "the certainty of experimental inquiry is here shut out," I sketch the nebular theory as enunciated by Kant and Laplace, and afterward proceed thus:
"Accepting some such view of the construction of our system as probable, a desire immediately arises to connect the present life of our planet with the past. We wish to know something of our remotest ancestry. On its first detachment from the sun, life, as we understand it, could not have been present on the earth. How, then, did it come there? The thing to be encouraged here is a reverent freedom—a freedom preceded by the hard discipline which checks licentiousness in speculation—while the thing to be repressed, both in science and out of it, is dogmatism. And here I am in the hands of the meeting, willing to end but ready to go on. I have no right to intrude upon you unasked the unformed notions which are floating like clouds or gathering to more solid consistency in the modern speculative mind."
I then notice more especially the theory of evolution:
"Those who hold the doctrine of evolution are by no means ignorant of the uncertainty of their data, and they only yield to it a provisional assent. They regard the nebular hypothesis as probable; and, in the utter absence of any proof of the illegality of the act, they prolong the method of Nature from the present into the past. Here the observed uniformity of Nature is their only guide. Having determined the elements of their curve in a world of observation and experiment, they prolong' that curve into an antecedent world, and accept as probable the unbroken sequence of development from the nebula to the present time."
Thus it appears that, long antecedent to the publication of his advice, I did exactly what Prof. Virchow recommends, showing myself as careful as he could be not to claim for a scientific doctrine a certainty which did not belong to it.
I now pass on to the "Belfast Address," and will cite at once from it the passage which has given rise to the most violent animadversion:
"Believing as I do in the continuity of Nature, I cannot stop abruptly where our microscopes cease to be of use. At this point the vision of the mind authoritatively supplements that of the eye. By an intellectual necessity I cross the boundary of the experimental evidence, and discern in that 'matter' which we, in our ignorance of its latent powers, and notwithstanding our professed reverence for its Creator, have hitherto covered with opprobrium, the promise and potency of all terrestrial life."
Without halting for a moment I go on to do the precise thing which Prof. Virchow declares to be necessary:
