Looking round him on his entrance into life, and asking himself what was his place and business in it, he turned for examples to his fellow-men, and found little that he could venture to imitate. Whatever they professed, they all really guided themselves by their different notions of what they thought desirable; and these notions themselves resting on no more secure foundation than a vague, inconsistent experience, the experience of one not being the experience of another, men were all, so to say, rather playing experiments with life than living, and the larger portion of them miserably failing. Their mistakes arising, as it seemed to Spinoza, from inadequate knowledge, things which at one time looked desirable disappointing expectation when obtained, and the wiser course concealing itself often under an uninviting exterior, he desired to substitute certainty for conjecture, and endeavour to find, by some surer method, where the real good of man lay. All this may sound very Pagan, and perhaps it is so. We must remember that he had been brought up a Jew, and had been driven out of the Jews' communion; his mind was therefore in contact with the bare facts of life, with no creed or system lying between them and himself as the interpreter of it. Some true account of things, however, he thought it likely that there must be, and the question was, how to find it. Of all forms of human thought, but one, he reflected, would admit of the certainty which he required--the mathematical; and, therefore, if certain knowledge were attainable at all, it must be looked for under the mathematical or demonstrative method; by tracing from ideas clearly conceived the consequences which were formally involved in them. The question was, therefore, of these ideas, these verae ideae, as he calls them,--what were they, and how were they to be obtained: if they were to serve as the axioms of his system, they must, he felt, be self-evident truths, of which no proof was required; and the illustration which he gives of the character of such ideas is ingenious and Platonic. In order to produce any mechanical instrument, he says, we require others with which to manufacture it; and others again to manufacture those; and it would seem thus as if the process must be an infinite one, and as if nothing could ever be made at all. Nature, however, has provided for the difficulty in creating of her own accord certain rude instruments, with the help of which we can make others better; and others again with the help of those. And so he thinks it must be with the mind, and there must be somewhere similar original instruments provided also as the first outfit of intellectual enterprise. To discover them, he examines the various senses in which men are said to know anything, and he finds that these senses resolve themselves into three, or, as he elsewhere divides it, four:-- We know a thing,