On the subject of materialism, Mr. Locke seems to have had two opinions; the first, that as far as we can discern, the properties of mind and matter are utterly distinct and irreconcileable; the second, that God might for aught we know be able to superadd to matter a faculty of thinking: either the one or the other of these opinions must be without meaning. In speaking of the difficulties attending both sides of this question, he has, however, offered one of the best moral cautions against precipitancy of judgment and impatience of inquiry to be found in any author. He says, (vol. ii. p. 203:) ‘He that considers how hardly sensation is in our thoughts reconcilable to extended matter, or existence to any thing that hath no extension at all, will confess that he is very far from certainly knowing what his soul is. It is a point which seems to me to be put out of the reach of our knowledge: and he who will give himself leave to consider freely, and look into the dark and intricate part of each hypothesis, will scarce find his reason able to determine him fixedly for or against the soul’s materiality. Since on which side soever he views it, either as an unextended substance, or a thinking extended matter, the difficulty to conceive either, will, whilst either alone is in his thoughts, still drive him to the contrary side. An unfair way which some men take with themselves; who because of the unconceivableness of some thing they find in one, throw themselves violently into the contrary hypothesis, though altogether as unintelligible to an unbiassed understanding. This serves not only to show the weakness and scantiness of our knowledge, but the insignificant triumph of such sort of arguments, which drawn from our own views may satisfy us that we can find no certainty on one side of the question; but do not at all thereby help us to truth, by running into the opposite opinion, which on examination will be found clogged with equal difficulties.’