The reasons are: (a) First love, which means love before marriage and immediately after marriage, is somewhat affected by sexual love, that is, by the ardour which belongs to the body and has not been modified by spiritual love. [2] (b) A person proceeds by stages from natural to spiritual. He becomes spiritual as his rational faculty, held midway between heaven and the world, begins to draw breath from heavenly influence, which happens as he is affected and pleased by wisdom (on this see 130 above). To the extent that this happens, his mind is lifted into a higher atmosphere which holds heavenly light and heat, or, what is the same, the wisdom and love enjoyed by the angels. For heavenly light acts as one with wisdom, heavenly heat with love. As the wisdom and the love of it increase in married couples, so their conjugial love is purified. Since this takes place by stages, it follows that this love becomes more and more chaste. This spiritual purification can be compared with the purification of natural spirits practised by chemists, what they call defecation, rectification, castigation, distillation, refining, decantation and sublimation. Purified wisdom can be compared with alcohol, which is the highest degree of rectified spirit. [3] (c) Spiritual wisdom then has the essential quality of growing warmer the more wisdom is loved, so that it goes on increasing for ever. This happens by the processes of defecation, castigation, rectification, refining, decantation and sublimation; and these take place by means of the process of refining and distancing the intellect from the fallacies of the senses, and the will from the snares of the body. It is plain from this that likewise conjugial love, which is the child of wisdom, by stages becomes more and more pure and so chaste. The first state of love between a married couple is one of heat not yet moderated by light, but it is by stages moderated as the husband's wisdom becomes more perfect, and his wife loves this in her husband; see the experience in 137.