The pathological fixed idea is "parasitic," automatic, discordant, irresistible. Obsession is only a special case of psychic disintegration, a kind of doubling of consciousness. The individual becomes a person "possessed," whose self has been confiscated for the sake of the fixed idea, and whose submission to his situation is wrought with pain.
In spite of this parallel the distinguishing criterion between the two is very vague, because from the sane to the delirious idea the transitions are very numerous. We are obliged to recognize "that with certain workers--who are rather taken up with the elaboration of their work, and not masters directing it, quitting it, and resuming it at their pleasure--an artistic, scientific, or mechanical conception succeeds in haunting the mind, imposing itself upon it even to the extent of causing suffering." In reality, pure psychology is unable to discover a positive difference between obsession leading to creative work and the other forms, because in both cases the mental mechanism is, at bottom, the same. The criterion must be sought elsewhere. For that we must go out of the internal world and proceed objectively. We must judge the fixed idea not in itself but by its effects. What does it produce in the practical, esthetic, scientific, moral, social, religious field? It is of value according to its fruits. If objection be made to this change of front we may, in order to stick to a strictly psychological point of view, state that it is certain that as soon as it passes beyond a middle point, which it is difficult to determine, the fixed idea profoundly troubles the mechanism of the mind. In imaginative persons this is not rare, which partly explains why the pathological theory of genius (of which we shall speak later) has been able to rally so many to its support and to allege so many facts in its favor.
[30] For the distinction between this form of imagination and the two others (fixed, objectified), I refer the reader to the Conclusion of this work, where the subject will be treated in detail.
[31] Colozza, _L'immaginazione nella Scienza_, Rome, 1900, pp. 111 ff.
[32] This unifying, organizing, creative principle is so active in certain minds that, placed face to face with any work whatever--novel, picture, monument, scientific or philosophic theory, financial or political institution--while believing that they are merely considering it, they spontaneously remake it. This characteristic of their psychology distinguishes them from mere critics.