A cause cannot be physically separated from its effect any more than the visible can be separated from the eye, the taste from the tongue, in brief the general from the concrete. Nevertheless, the faculty of thought may separate the one from the other. We must keep in mind that this separation is a mere formality of thought, although it is a formality which is necessary in order to be reasonable or conscious, in order to act scientifically. The practice of understanding, or scientific practice, derives the concrete from the general, the natural things from nature. But whoever has been behind the scenes, and has looked at the faculty of thought at work, knows that, conversely the general is derived from the concrete, the concept of nature from natural things. The theory of understanding or science teaches us that the antecedent is understood by its consequent, the cause by its effect, while our practical understanding regards the after as a consequence of the before, the effect as a result of the cause. The faculty of understanding, the organ of generalization, regards its opposite, the concrete, as secondary, while the faculty of thought which understands itself regards it as primary. However, the practice of understanding is not to be changed by its theory, nor can it be; the theory intends simply to render the steps of consciousness firm. The scientific farmer differs from the practical farmer, not because he employs theory and method, for both do that, but because he understands the theory, while the practical man theorizes instinctively. To continue: From a given multitude of facts, reason generates truth in general, and out of a succession of forms and transformations it abstracts the true cause, just as absolute multiplicity is the nature of space, so absolute variability is the nature of time. Every particle of time and space is new, original, and has never been there before. The faculty of thought enables us to find our way through this absolute medley by abstracting general concepts out of the multitude of things in space, and tracing the variations of time to general causes. The entire nature of reason consists in generalizing sense perceptions, in abstracting the common elements out of concrete things. Whoever does not fully understand reason by understanding that it is the organ of generalization forgets that understanding requires an object which must remain something outside of its conception, since such object cannot be dissolved by its conception. The being of the reasoning faculty cannot be understood any more than being in general. Or rather, being is understood when we take it in its generality. Not being itself, but the general element of being, is understood by the faculty of thought.