Page:Popular Science Monthly Volume 16.djvu/670

 into certain chemical compounds, we can not infer from this that protoplasm is one of these compounds. What characterizes a chemical compound is fixity of composition. But protoplasm changes incessantly, without modifying any of its fundamental properties. New substances are constantly entering into its mass while others are leaving it. Protoplasm is perpetually decomposing and recomposing itself. It is this, and not its chemical composition, that characterizes it. It is always in movement, and motion characterizes life.

Life is, then, only a combination of movements, or, if you please, a mode of movement of which certain substances are alone capable, and which is not without analogy with the whirling movements to which eminent physicists attribute the properties of chemical atoms. We might pursue this comparison between atoms and protoplasms, and use it to show that the latter must have been formed originally in the greatest possible number; that we seem to be powerless to reproduce them; that they appeared with a train of properties which have controlled their subsequent destiny; and that they had from the first the individuality we see in them at the present day.



O say that we are under a moral obligation to enjoy ourselves would be, in the opinion of most persons, to utter an unmeaning paradox. It is commonly supposed that the natural instinct for pleasure can take care of itself without any reënforcement from a sense of duty. More than this, our habits of thought instinctively lead us to set duty in antagonism to pleasure, so that to talk of a duty of enjoyment sounds self-contradictory. Many influences have combined in the past history of our race to produce this conception of the relation of pleasure and duty. Unless this idea had been developed and fixed in the human mind, it is difficult to see how the moral progress already attained would have been possible. Even that extreme form of this doctrine of the antagonism of pleasure and duty involved in the ascetic renunciation of all enjoyment as sinful was doubtless a useful and necessary belief in certain stages of social evolution. But it may be that this conception of pleasure has now lost its utility, and will have to be displaced by a view of life which sets a positive moral value on enjoyment. The epicurean theory that all good resolves itself into pleasure has long been before the world, and has won many adherents. Since the revival of letters many writers have contended warmly against the mediaeval disparagement of pleasure. Of late years a number of writers with a keen appreciation of the æsthetic resources at our command have in beautiful and alluring language held up a 