The important thing to realize is that the conjuring up of the idea is not a deliberate, voluntary act. It is something that happens to us rather than something we do.
To be genuinely thoughtful, we must be willing to sustain and protract that state of doubt which is the stimulus to thorough enquiry, so as not to accept an idea or make a positive assertion of a belief, until justifying reasons have been found.
New associations and fresh ideas are more likely to come out of a varied store of memories and experience than out of a collection that is all of one kind.
The most characteristic circumstances of an intuition are a period of intense work on the problem accompanied by a desire for its solution, abandonment of the work perhaps with attention to something else, then the appearance of the idea with dramatic suddenness and often a sense of certainty. Often there is a feeling of exhilaration and perhaps surprise that the idea had not been thought of previously.