Selection from Divine Love and Wisdom ~ Emanuel Swedenborg
Every man is born into a capacity to understand truths even to the inmost degree in which the angels of the third heaven are; for the human understanding, rising up by continuity around the two higher degrees, receives the light of their wisdom .... Therefore man has the ability to become rational according to his elevation; if raised to the third degree he becomes rational from that degree, if raised to the second degree he becomes rational from that degree, if not raised he is rational in the first degree. It is said that he becomes rational from those degrees, because the natural degree is the general receptacle of their light. The reason why man does not become rational to the height that he might is, that love, which is of the will, cannot be raised in the same manner as wisdom, which is of the understanding. Love, which is of the will, is raised only by fleeing from evils as sins, and then by goods of charity, which are uses, which the man thereafter performs from the Lord. Consequently, when love, which is of the will, is not at the same time raised, wisdom, which is of the understanding, however it may have ascended, falls back again down to its own love. Therefore, if man's love is not at the same time raised into the spiritual degree, he is rational only in the lowest degree. From all this it can be seen that man's rational is in appearance as if it were of three degrees, a rational from the celestial, a rational from the spiritual, and a rational from the natural; also that rationality, which is the capacity whereby man is elevated, is still in man whether he be elevated or not.[It has been said that every man is born into that capacity, namely, rationality, but by this is meant every man whose externals have not been injured by some accident, either in the womb, or by some disease after birth, or by a wound inflicted on the head, or in consequence of some insane love bursting forth, and breaking down restraints. In such the rational cannot be elevated; for life, which is of the will and understanding, has in such no bounds in which it can terminate, so disposed that it can produce outmost acts according to order; for life acts in accordance with outmost determinations, though not from them. That there can be no rationality with infants and children. ...]
(Divine Love and Wisdom 258 - 259)