447. (3) Fornication is the mark of a natural person. It is the mark of a natural person just as a love for the opposite sex is, which, if it becomes active before marriage, is called fornication. Every person is born carnal, becomes sensual, then natural, and gradually rational; and if he does not stop there, he becomes spiritual. He develops in this way in order that planes of existence may be formed for higher planes to rest on, like a palace on its foundations. The lowest plane with the things built on it may also be likened to a piece of ground, in which, having been prepared, noble seeds are planted. [2] As regards love for the opposite sex in particular, it, too, is at first carnal, for it begins in the flesh. It then becomes sensual, for the five senses take delight from its general sensation. After that it becomes natural, being much like the same love in animals, because it is an indiscriminate love for the opposite sex. However, because the human being was born to become spiritual, it later becomes naturally rational, and from being naturally rational, spiritual, and finally spiritually natural; and at that point the now spiritual love flows into and acts upon the rational love, and through that the sensual love, and through that finally the love that is in the body and flesh. Thus, because these last form its lowest plane, it acts upon it spiritually, and at the same time rationally and sensually. It flows in and acts upon these planes sequentially when a person thinks about it, but simultaneously when he is in the lowest plane. [3] Fornication is the mark of a natural person because it flows directly from a natural love for the opposite sex. This love may be naturally rational, but not spiritual, because a love for the opposite sex cannot become spiritual until it becomes conjugial love. From being natural, love for the opposite sex becomes spiritual when a person turns away from indiscriminate lust and devotes himself to one, to whose soul he unites his soul.