The acquaintance had begun about 1851; there was a common bond in their sea experiences and explorations, as well as in their search after a wider philosophy, to include the teachings of natural science; the older man found in the younger a source of much biological and other information, a suggestive critic and a stimulating companion.  Their relations took a long step towards intimacy after 1861, when, after the loss of her eldest child, Mrs. Huxley and her other children made a long stay at Down, and entered upon a life-long friendship with Mrs. Darwin and the family.  Thereafter followed many visits to Down, and, whenever Darwin was in London, the certainty of half-an-hour’s keen talk—­all that the doctor allowed—­with his friend and fellow-worker on some critical question of the moment.

Darwin’s admiration of his friend’s powers was outspoken.  To quote one or two expressions of it:  Huxley had delivered, in 1862, six lectures to working men, which were printed off each week as delivered in “little green pamphlets,” under the general title of “On Our Knowledge of the Causes of the Phenomena of Organic Nature,” winding up with an account of the bearing of the Origin upon the complete theory of these causes.  Acknowledging Nos.  IV and V, Darwin writes:—­

They are simply perfect.  They ought to be largely advertised; but it is very good in me to say so, for I threw down No.  IV with this reflection:  “What is the good of me writing a thundering big book when everything is in this green little book, so despicable for its size?” In the name of all that is good and bad, I may as well shut up shop altogether.

After reading the article “Mr. Darwin’s Critics” in 1871, he wrote yet more enthusiastically.  Mr. Mivart, in an apologia for the attitude of Roman Catholicism towards Evolution, twitted the generality of men of science with their ignorance of the real doctrines of his Church, and cited the Jesuit theologian, Suarez, the latest great representative of scholasticism, as following St. Augustine in asserting derivative creation—­that is, evolution from primordial matter endowed with certain powers.  Huxley thereupon examined the works of the learned Jesuit, and found not only that the particular reference was not to the point, but that, in his tract on the “Six Days of Creation,” Suarez expressly rejects the doctrine and reprehends Augustine for holding it.  “So,” write Huxley gleefully at the irony of the situation, “I have come out in the new character of a defender of Catholic orthodoxy, and upset Mivart out of the mouth of his own prophet.”

In the course of a most appreciative letter Darwin exclaimed:—­

What a wonderful man you are to grapple with those old metaphysico-divinity books....  The pendulum is now swinging against our side, but I feel positive it will soon swing the other way; and no mortal man will do half as much as you in giving it a start in the right direction, as you did at the commencement.

And then, after “mounting climax on climax,” he adds: