Among the recollections that are lifelong, I have one as vivid as ever after more than twenty-five years have elapsed; it is of an evening lecture - the first of a series - given at South Kensington to working men. The lecturer was Professor Huxley; his subject, the Common Lobster. All the apparatus used was a good-sized specimen of the creature itself, a penknife, and a black-board and chalk. With such materials the professor gave us not only an exposition, matchless in its lucidity, of the structure of the crustacea, but such an insight into the purposes and methods of biological study as few could in those days have anticipated. For there were as yet no Science Primers, no International Series; and the "new biology" came upon us like the revelation of another world. I think that lecture gave me, what I might otherwise never have got (and what some people never get), a profound conviction of the reality and meaning of facts in nature. That impression I have brought to the attempt which this little book embodies. The facts of nature are God's revelation, of the same weight, though not the same in kind, as His written Word.