In order to produce any mechanical instrument, Spinoza 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; there must be somewhere similar original instruments provided also as the first outfit of intellectual enterprise. To discover these, he examines the various senses in which men are said to know anything, and he finds that they resolve themselves into three, or, as he elsewhere divides it, four.
We know a thing—
| 1. | i. | Ex mero auditu: because we have heard it from some person or persons whose veracity we have no reason to question. |
| ii. | Ab experientiâ vagâ: from general experience: for instance, all facts or phenomena which come to us through our senses as phenomena, but of the causes of which we are ignorant. | |
| 2. | We know a thing as we have correctly conceived thelaws of its phenomena, and see them following in their sequencein the order of nature. | |
| 3. | Finally, we know a thing, ex scientiâ intuitivâ, whichalone is absolutely clear and certain. |
To illustrate these divisions, suppose it be required to find a fourth proportional which shall stand to the third of three numbers as the second does to the first. The merchant's clerk knows his rule; he multiplies the second into the third and divides by the first. He neither knows nor cares to know why the result is the number which he seeks, but he has learnt the fact that it is so, and he remembers it.
A person a little wiser has tried the experiment in a variety of simple cases; he has discovered the rule by induction, but still does not understand it.
A third has mastered the laws of proportion mathematically, as he has found them in Euclid or other geometrical treatise.
A fourth, with the plain numbers of 1, 2, and 3, sees for himself by simple intuitive force that 1:2=3:6.
Of these several kinds of knowledge the third and fourth alone deserve to be called knowledge, the others being no more than opinions more or less justly founded. The last is the only real insight, although the third, being exact in its form, may be depended upon as a basis of certainty. Under this last, as Spinoza allows, nothing except the very simplest truths, non nisi simplicissimæ veritates, can be perceived; but, such as they are, they are the foundation of all after-science; and the true ideas, the veræ ideæ, which are apprehended by this faculty of intuition, are the primitive instruments with which nature has furnished us. If we ask for a test by which to distinguish them, he has none to give us. 'Veritas,' he says to his friends, in answer to their question, 'veritas index sui est et falsi. Veritas se ipsam patefacit.' All original truths are of such a kind that they cannot without absurdity even be conceived to be false; the opposites of them are contradictions in terms.—'Ut sciam me scire, necessario debeo prius scire. Hinc patet quod certitudo nihil est præter ipsam essentiam objectivam.... Cum itaque veritas nullo egeat signo, sed sufficiat habere essentiam rerum objectivam, aut quod idem est ideas, ut omne tollatur dubium; hinc sequitur quod vera non est methodus, signum veritatis quærere post acquisitionem idearum; sed quod vera methodus est via, ut ipsa veritas, aut essentiæ objectivæ rerum, aut ideæ (omnia illa idem significant) debito ordine quærantur.' (De Emend. Intell.)
Spinoza will scarcely carry with him the reasoner of the nineteenth century in arguments like these. When we remember the thousand conflicting opinions, the truth of which their several advocates have as little doubted as they have doubted their own existence, we require some better evidence than a mere feeling of certainty; and Aristotle's less pretending canon promises a safer road. Ὁ πασι δοκει, 'what all men think,' says Aristotle, τουτο ειναι φαμεν 'this we say is,'—'and if you will not have this to be a fair ground of conviction, you will scarcely find one which will serve you better.' We are to see, however, what these ideæ are which are offered to us as self-evident. Of course, if they are self-evident, if they do produce conviction, nothing more is to be said; but it does, indeed, appear strange to us that Spinoza was not staggered as to the validity of his canon, when his friends, everyone of them, so floundered and stumbled among what he regarded as his simplest propositions; when he found them, in spite of all that he could say, requiring endless signa veritatis, and unable for a long time even to understand their meaning, far less to 'recognise them as elementary certainties.' Modern readers may, perhaps, be more fortunate. We produce at length the definitions and axioms of the first book of the 'Ethica,' and they may judge for themselves:—
DEFINITIONS.