everything without which the effect is incapable of being produced, is of necessity a cause; but a cause not absolutely. For the cause sine quâ non is not Synectic, but Co-operative. And everything that acts produces the effect, in conjunction with the aptitude of that which is acted on. For the cause disposes. But each thing is affected according to its natural constitution; the aptitude being causative, and occupying the place of causes sine quâ non. Accordingly, the cause is inefficacious without the aptitude; and is not a cause, but a co-efficient. For all causation is conceived in action. Now the earth could not make itself, so that it could not be the cause of itself. And it were ridiculous to say that the fire was not the cause of the burning, but the logs,—or the sword of the cutting, but the flesh,—or the strength of the antagonist the cause of the athlete being vanquished, but his own weakness.