The speculative interest is more permanent than the empirical. It rests primarily on the perception of the relations of cause and effect; it seeks to know the reasons of things. On this account it is a higher form of apperception, or mental assimilation. The most fundamental idea in the speculative interest is that of purpose. We want to know the _purpose of things_, the function they are to perform, the end they are expected to reach. Thus a child has a key to the understanding of even so complicated a machine as a self-binder, or a printing press, provided he sees clearly the purpose of each. Until this is perceived the facts are an unintelligible jumble of particulars. A crude form of the speculative interest is seen very early in the child, when he demands a reason for everything. It always remains the mainspring of intellectual life; when it ceases to be a motive power to thinking, thought is dead.
The æsthetic interest rests upon the enjoyment of contemplation, when an _ideal_, sometimes distinct, sometimes vague, can be perceived through a _sense medium_. In the Greek statue of _Apollo Belvidere_, a divinity is represented in marble. In the painting, _Breaking Home Ties_, the feelings of a lad and his mother upon parting are portrayed upon canvas. In music the ideal is usually vague, in poetry it is clear and distinct. The æsthetic value of the latter is enhanced by good oral recitation, both because appeal is made to an additional sense, and because the ears of men were attuned to beautiful poetry long before the eye learned to apprehend it.
All of these interests, the empirical, the speculative, and the æsthetic, may be classed as _individual_, since they rest upon purely subjective grounds. They might belong to any Robinson Crusoe who became isolated from his fellows. But the remaining groups, the sympathetic, the social, and the religious, rest upon the idea of intercourse with others. They are, therefore, of supreme importance for civilized life. Without the sympathetic coöperation of men civilization would become impossible. Mephistopheles in “Faust” defines himself as “the Spirit that ever denies.”[12] Consequently any man who becomes so absorbed in his individual concerns as to deny all social duties and renounce all social benefits becomes thereby a kind of civic devil. The cynics of old repudiated all social obligations, thus making themselves bitter civic devils, while the Cyrenaics, choosing self-indulgence, but denying likewise social duties, transformed themselves into sensualistic civic devils.