2. These two in Ethics are classed together.
As we have correctly conceived the laws of such phenomena, and see them following in their sequence m the order of nature.
3. Ex scientia intuitiva: which alone 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 simplicissimae veritates can be perceived, but, such as they are, they are the foundation of all after science; and the true ideas, the verae ideae, 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." These 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 pater quod certitudo nihil est praeter ipsam essentiam objectivam. …Cum itaque veritas nullo egeat signo, sed sufficiat habere essentiam rerum objectivam, aut quod idem est ideas, ut omne tollatur dubium; hint sequitur quod vera non est methodus, signum veritatis quaerere post acquisitionem idearum; sed quod vera methodus est via, et ipsa vetitas, aut essentiae objectivae rerum, aut ideae (omnia illa idem significant) debito ordine quaerantur." (De Emend. Intell.)
The opinion of this Review on reasonings of such a kind has been too often expressed to require us now to say how insecure they appear to us. 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. Ho pasi dokei, "what all men think," says Aristotle, touto einai phamen, "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 idete are which Spinoza offers as self-evident. All will turn upon that; for, 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, every one of them, so floundered and stumbled among what he regarded as his simplest propositions, requiring endless signa veritalis, and unable for a long time even to understand their meaning, far less to "recognize 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:—