We may meet a person who seems to be very stupid, but who has brought with himself a concealed higher life that needs only to be brought out. Most human beings these days are much further than it seems, and more people would know about this if the materialism of our conditions and of our time would not drive them back into the inner life of the soul. A large percentage of today’s human beings was previously much further advanced. Whether that which is within them will come forth depends on many factors. But it is possible to give some help. Suppose you have before you a person who was highly developed in his earlier incarnation, but now has an undeveloped brain. An undeveloped brain may at times conceal great spiritual faculties. But if he can be taught the usual everyday abilities, it may happen that the inner spirituality also comes forth.
Another important factor is the environment in which a person lives. The human being is a mirror-image of his surroundings in a most significant way. Suppose that a person is a highly developed personality, but lives in surroundings that awaken and develop certain prejudices with such a strong effect that the higher talents cannot come forth. Unless such a person finds someone who can draw out these abilities, they will remain hidden.
Source: Rudolf Steiner – GA 54 – Esoteric Development: Lecture I: Inner Development – Berlin, 7th December 1905