All their struggles, their discipline, their battles, their failures, their successes, were for you and me.  Man has had the experience of all the animals below him.  He has suffered and struggled as a fish, he has groveled and devoured as a reptile, he has fought and triumphed as a quadruped, he has lived in trees as a monkey, he has inhabited caves with the wolf and the bear, he has roamed the forests and plains as a savage, he has survived without fire or clothes or weapons or tools, he has lived with the mastodon and all the saurian monsters, he has held his own against great odds, he has survived the long battles of the land and the sea, he weathered the ice-sheet that overrode both hemispheres, he has seen many forms become extinct.  In the historic period he has survived plague and pestilence, and want and famine.  What must he have survived in prehistoric times!  What must he have had to contend with as a cave-dweller, as a tree-dweller, as a river-drift man!  Before he had tools or weapons what must he have had to contend with!

Nature was full of sap and rioted in rude strength well up to Quaternary times, producing extravagant forms which apparently she had no use for, as she has discontinued them.

In all these things you and I had our part and lot; of this prodigal outpouring of life we have reaped the benefit; amid these bizarre forms and this carnival of lust and power, the manward impulse was nourished and forwarded.  In Eocene times nearly half the mammals lived on other animals; it must have been an age of great slaughter.  It favored the development of fleetness and cunning, in which we too have an interest.  Our rude progenitor was surely there in some form, and escaped the slaughter.  Then or later it is thought he took to the trees to escape his enemies, as the rats in Jamaica have taken to the trees to escape the mongoose.  To his tree-climbing we probably owe our hand, with its opposing thumb.

In all his disguises he is still our ancestor.  His story reads like a fairy book.  Never did nimble fancy of childhood invent such transformations—­only the transformations are so infinitely slow, and attended with such struggle and suffering.  Strike out the element of time and we have before us a spectacle more novel and startling than any hocus-pocus or legerdemain that ever set the crowd agape.

In every form man has passed through, he left behind some old member or power and took on some new.  He left his air-bladder and his gills and his fins with the fishes; he got his lungs from the dipnoans, the precursors of the amphibians, and from these last he got his four limbs; he left some part of his anatomy with the reptile, and took something in exchange, probably his flexible neck.  Somewhere along his line he picked up the four-chambered heart, the warm blood, the placenta, the diaphragm, the plantigrade foot, the mammary glands—­indeed, what has he not picked up on the long road of his many transformations?