The single and outstanding characteristic of the conception of god at all times and under all conditions is that it is the equivalent of ignorance. In primitive times it is ignorance of the character of natural forces that leads to the assumption of the existence of gods, and in this respect the god-idea has remained true to itself throughout. Even to-day whenever the principle of "God" is invoked a very slight examination is enough to show that the only reason for this being done is our ignorance of the subject before us. Why does anyone assume that we must believe in God in order to explain the beginnings of life? Why is "God" assumed to be responsible for the order of nature? Why must we assume "God" to explain mind? The answer to these and to all similar questions is that we do not know, in the sense that we know the cause of planetary motions, how these things came to be. It is not what we know about them that leads to the assumption of god, but what we do not know. And the converse of that is that so soon as knowledge replaces ignorance "God" will be dispensed with. It is never a case of believing in God because of the actual knowledge we possess, but always the appeal to weakness and ignorance. From this point of view the colloquial "God only knows!" expresses the appeal to ignorance even more clearly than the elaborate argument of the sophisticated apologist. This aspect of the matter was well put by Spinoza. Believers in the argument from design, he says, have a method of argument that is a reduction, not to the impossible, but to ignorance. Thus, If a stone falls from a roof on to someone's head and kills him, they will demonstrate by their new method that the stone fell to kill the man; for if it had not by God's will fallen with that object, how could so many circumstances (and there are often many concurrent circumstances) have all happened together by chance. Perhaps you will answer that the event is due to the facts that the wind was blowing, and the man was walking that way. "But why," they will insist, "was the wind blowing, and why was the wind at that very time blowing that way?" If you again answer, that the wind had then sprung up because the sea had begun to be agitated the day before, the weather having been previously calm, and that the man had been invited by a friend, they will again insist: "But why was the sea agitated, and why was the man invited at that time?" So they will pursue their question from cause to cause, till at last you take refuge in the will of God--in other words, the sanctuary of ignorance. (Appendix to _Ethics_; pt. 1)