[21] _Mental Evolution in Animals_, pp. 155-8. [22] [I have put 'may' in place of 'do' for the sake of argument.--ED.] II. Suppose the man who found the watch upon a heath to continue his walk till he comes down to the sea-shore, and suppose further that he is as ignorant of physical geography as he is of watch-making. He soon begins to observe a number of adaptations of means to ends, which, if less refined and delicate than those that formed the object of his study in the watch, are on the other hand much more impressive from the greatly larger scale on which they are displayed. First, he observes that there is a beautiful basin hollowed out in the land for the reception of a bay; that the sides of this basin, which from being near its opening are most exposed to the action of large rolling billows, are composed of rocky cliffs, evidently in order to prevent the further encroachment of the sea, and the consequent destruction of the entire bay; that the sides of the basin, which from being successively situated more inland are successively less and less exposed to the action of large waves, are constituted successively of smaller rocks, passing into shingle, and eventually into the finest sand: that as the tides rise and fall with as great a regularity as was exhibited by the movements of the watch, the stones are carefully separated out from the sand to be arranged in sloping layers by themselves, and this always with a most beautiful reference to the places round the margin of the basin which are most in danger of being damaged by the action of the waves. He would further observe, upon closer inspection, that this process of selective arrangement goes into matters of the most minute detail. Here, for instance, he would observe a mile or two of a particular kind of seaweed artistically arranged in one long sinuous line upon the beach; there he would see a wonderful deposit of shells; in another place a lovely little purple heap of garnet sand, the minute particles of which have all been carefully picked out from the surrounding acres of yellow sand. Again, he would notice that the streams which come down to the bay are all flowing in channels admirably dug out for the purpose; and, being led by curiosity to investigate the teleology of these various streams, he would find that they serve to supply the water which the sea loses by evaporation, and also, by a wonderful piece of adjustment, to furnish fresh water to those animals and plants which thrive best in fresh water, and yet by their combined action to carry down sufficient mineral constituents to give that precise degree of saltness to the sea as a whole which is required for the maintenance of pelagic life. Lastly, continuing his investigations along this line of inquiry, he would find that a thousand different habitats were all thoughtfully adapted to the needs of a hundred thousand different forms of life, none of which could survive if these habitats were reversed.