As we reached further and further back through the stream of time, the task became easier in a way; but we have had to generalize more, and often, for want of time and space, to use types in lieu of individuals. For with every successive generation the number of our progenitors increased in geometrical progression (as in the problem of the nails in the horseshoe) until a limit of numbers was reached--namely, the sum of the inhabitants of the terrestrial globe. In the seventh century there was not a person living in France (not to mention Europe) who was not in the line of our direct ancestry, excepting, of course, those who had died without issue and were mere collaterals. [Illustration: "THE MAMMOTH."] We have even just been able to see, as in a glass darkly, the faint shadows of the Mammoth and the cave bear, and of the man who hunted and killed and ate them, that he might live and prevail. The Mammoth! We have walked round him and under him as he browsed, and even _through_ him where he lay and rested, as one walks through the dun mist in a little hollow on a still, damp morning; and turning round to look (at the proper distance) there was the unmistakable shape again, just thick enough to blot out the lines of the dim primeval landscape beyond, and make a hole in the blank sky. A dread silhouette, thrilling our hearts with awe--blurred and indistinct like a composite photograph--merely the _type_, as it had been seen generally by all who had ever seen it at all, every one of whom _(exceptis excipiendis)_ was necessarily an ancestor of ours, and of every man now living. There it stood or reclined, the monster, like the phantom of an overgrown hairy elephant; we could almost see, or fancy we saw, the expression of his dull, cold, antediluvian eye--almost perceive a suggestion of russet-brown in his fell. Mary firmly believed that we should have got in time to our hairy ancestor with pointed ears and a tail, and have been able to ascertain whether he was arboreal in his habits or not. With what passionate interest she would have followed and studied and described him! And I! With what eager joy, and yet with what filial reverence, I would have sketched his likeness--with what conscientious fidelity as far as my poor powers would allow! (For all we know to the contrary he may have been the most attractive and engaging little beast that ever was, and far less humiliating to descend from than many a titled yahoo of the present day.) Fate, alas, has willed that it should be otherwise, and on others, duly trained, must devolve the delightful task of following up the clew we have been so fortunate as to discover. * * * * *