(_b_) But more important than any intensity of picture-thinking to the growth and persistence of imagination-beliefs, is the want of a mental standard, by which they might be discredited. It is true that even at a low level of culture individuals are found for whom common sense constitutes a private standard, and who are sceptics in relation to their tribal beliefs.[92] But such a private standard cannot be communicated, and for the great majority of the tribesmen common sense is no confident guide; and perhaps they are even incapable of effectively comparing their ideas. At any rate, one reason why we believe our memories and not our imaginations is that, whilst in both cases the images (or elements of images) entering into them are derived from experience, in memory the relations of images in place, time and context are also derived directly from experience; whereas in imagination images (or their elements) are reconstructed in relations in which they have never been experienced, by analogies of experience (often distorted) or by condensations the most capricious. Therefore, to make imaginations credible to us, even in play, the relations of experience must be faithfully imitated, as (_e. g._) in _Robinson Crusoe_; or else our emotions must be so strongly excited as to possess our minds with the fiction to the exclusion of all criticism. But with immature minds observation of fact, outside the practical, repetitive, necessary course of life, is not exact and coherent; and, accordingly, their memories are not coherent, especially as to time-relations; so that, by comparison with such memories, irregular imaginations suffer little. There is not enough orderly memory or general knowledge to discredit even absurd imaginations; for so far as observation and memory are disorderly, generalisation, conscious or unconscious, is impossible. Hence not only traditionary myths may be monstrous and arbitrary, but occasional tales of private invention, amongst both children and savages, usually exhibit disconnected transitions and impossible happenings. Yet they satisfy the immature mind.