The most important distinction between the animal and man is this, that the animal is very near bound within the limits of its necessities, the greater part of its activities being necessary for self-preservation and the preservation of race. Like a retail shopkeeper, it has no large profit from the trade of life; the bulk of its earning must be spent in paying back the interest to its bank. Most of its resources are employed in mere endeavour to live. But man, in life's commerce, is a big merchant. He earns a great deal more than he is absolutely compelled to spend. Therefore there is a vast excess of wealth in man's life, which gives him the freedom to be useless and irresponsible to a great measure. There are large outlying tracts, surrounding his necessities, where he has objects that are ends in themselves. The animals must have knowledge, so that their knowledge can be employed for the useful purposes of their life. But there they stop. They must know their surroundings in order to take their shelter and seek their food, some properties of things in order to build their dwellings, and some signs of the different seasons in order to adapt themselves to the changes. Man also must know because he must live. But there he does not stop. He has the pure enjoyment of his knowledge, because that knowledge is freedom. Upon this foundation of surplus, science and philosophy thrive.