The line of march of all spirits is always progressive, never retrograde. They raise themselves gradually In the hierarchy of existence they never de… - Allan Kardec

Intellectual superiority is not always accompanied by an equal degree of moral superiority, and the greatest geniuses may have much to expiate. For this reason, they often have to undergo an existence inferior to the one they have previously accomplished, which is a cause of suffering for them the hindrances to the manifestation of his faculties thus imposed upon a spirit being like chains that fetter the movements of a vigorous man. The idiot may be said to be lame in the brain, as the halt is lame in the legs, and the blind, in the eyes.

The spirit acquires an increase of knowledge and experience in each of his corporeal existences. He loses sight of part of these gains during his reincarnation in matter, which is too gross to allow of his remembering them in their entirety; but he remembers them as a spirit. It is thus that some somnambulists give evidence of possessing knowledge beyond their present degree of instruction, and even of their apparent intellectual capacity. The intellectual and scientific inferiority of a somnambulist in his waking state, therefore, proves nothing against his possession of the knowledge he may display in his lucid state. According to the circumstances of the moment and the aim proposed, he may draw this knowledge from the stores of his own experience, from his clairvoyant perception of things actually occurring, or from the counsels which he receives from other spirits; but, in proportion as his own spirit is more or less advanced, he will make his statements more or less correctly.

As spirits transport themselves from point to point with the rapidity of thought, they may be said to see everywhere at the same time. A spirit's thought may radiate at the same moment on many different points; but this faculty depends on his purity. The more impure the spirit, the narrower is his range of sight. It is only the higher spirits who can take in a whole at a single glance.