21. A more or less normal idea held by persons who are not familiar with Spiritism is the belief that spirits must know all things and. possess supreme wisdom simply because they are free of matter. This is a serious mistake.
Since spirits are merely the souls of human beings, they do not suddenly reach perfection upon leaving their earthly envelope. The spirit's progress only occurs over time, and it is only successively that it gets rid of its imperfections and acquires the knowledge it lacks. It would also be illogical to believe that the spirit of a primitive or of a criminal could suddenly become wise and virtuous, just as it would be contrary to God's justice to believe that it would remain unevolved forever.
Since there are humans of all degrees of knowledge and ignorance, goodness and malice, the same applies to spirits. There are those who are only frivolous and playful; others who are deceitful, fraudulent, hypocritical, evil and vindictive, and still others who are possessed of sublime virtues and wisdom unknown upon the earth. Such diversity in the character of spirits is one of the most important points to consider because it explains the good or evil nature of the communications that may be received, and it is especially important to be able to distinguish between them.