how the most heterogeneous natural forces successively come into play in them. By this explanation the difference between transitory phenomena and permanent forms of operation, becomes exceedingly clear; and as, moreover, a whole section (§ 26) is devoted to the question, it will be sufficient here to give a brief sketch of it. The rule, by which a force of Nature manifests itself in the chain of causes and effects — consequently the link which connects it with them — is the law of Nature. But the confusion between forces of Nature and causes is as frequent as it is detrimental to clearness of thought. It seems indeed as though no one had accurately defined the difference between these conceptions before me, however great may have been the urgency for such a distinction. Not only are forces of Nature turned into causes by such expressions as, Electricity, Gravity, &c., are the cause of so-and-so, but they are even often turned into effects by those who search for a cause for Electricity, Gravity, &c. &c., which is absurd. Diminishing the number of the forces of Nature, however, by reducing one to another, as for instance Magnetism is in our days reduced to Electricity, is a totally different thing. Every true, consequently really primary force of Nature—and every fundamental chemical property belongs to these forces—is essentially a qualitas occulta, i.e. it does not admit of physical, but only of metaphysical explanation : in other words, of an explanation which transcends the world of phenomena. No one has carried this confusion, or rather identification, of causes with forces of Nature further than Maine de Biran in his "Nouvelles considerations des rapports du physique au moral," for it is essential to his philosophy. It is besides remarkable, that when he speaks of causes, he rarely uses the word cause alone, but almost always speaks of cause ou force, just as we have seen Spinoza above (§ 8) write ratio sive causa no less than eight times in the same page. Both
