capacity to take hold of things as they are. The old opinion that heat was caloric, served as a working hypothesis for the mind a long time. In the view of those who held it, it was satisfactory and adequate. But it never really got hold of heat, because it contradicted the nature of heat. The astronomers thought, for a long time, that they had come into relations of knowledge with the stars through the Ptolemaic conception of the heavenly bodies. They were mistaken, however. Their theory did not fit the real celestial order at all. As a work of genius, Spinoza’s Ethics is one of the most remarkable productions ever formulated by the human intellect, but it conducted the mind away from truth, rather than into relations with it. Locke began his work as a philosopher, as Descartes began his, by looking into his own mind. Descartes began by casting out everything that could be doubted. Locke began by making an inventory of what his mind contained. Descartes wanted to find out how much he could know, as measured by what remained after throwing out everything that could be doubted. Locke sought to see how little he could know, by putting the sensations and impressions he found in his mind on the witness stand, and getting them to tell how they came to be there, and where they came from. Descartes began by a study of the intelligence, the instrument of knowledge. Locke began by a study of the facts which, by some means or other, had found their way into his intelligence. Descartes got rid of every belief that could be doubted. Locke ran every idea out of his mind that had been imported from the outside world, in order that he might see if the mind had any constitutional power to produce any. Descartes, having dislodged all inherited beliefs, such as took for granted the existence of God, man, mind, and outer world, found some mental laws, capabilities, and tendencies left, which compelled a man, if he thought at all, to think in a given way; and if he thought on given lines, to think to a given conclusion. Not being able to get these laws out of the mind, he called them innate ideas. They were in the mind by structure and constitution. After Locke had carefully examined the contents of his mind, he declared they were all imported from an outside realm. Nothing he found in the mind was indigenous to the soil. When all foreign importations were removed, nothing remained but an empty vessel. The mind was nothing but a receptacle, into which the senses dumped such objects as they happened to find lying round loose in the outside world. It had no more power to understand or turn into thought what was brought in than a piece of white paper had to read and interpret what was written upon it; or than a kettle to recognize the liquid making up its contents as water. It is like a table of wax; any sort of letters may be graven upon it, but the table cannot read them.