We say, from its first warmth to its first fire, because vital heat is love, and conjugial heat or love grows progressively until it, so to speak, bursts forth into flame or fire. We say, to its first fire, because we mean the first state after the wedding, when that love burns. What happens to it after this first fire, when the marriage continues, has been described in the preceding chapters. In this part of the study its sequence from the starting block to this first goal has been explained.

[2] Every sequence advances from the first state to the last, and the last becomes the first stage of a following sequence; and everything in an intermediate sequence is the last stage of an earlier and the first stage of a later sequence. Thus by causes ends advance continually towards effects. All this can be well enough proved and illustrated to the reason from what is known and can be seen in the world. But since the only subject under discussion here is the sequence in which love advances from its first stage to its goal, the general discussion can be omitted and here we shall only say that whatever was the nature of the sequence followed by this love from its first warmth to its first fire, such also is usually its nature inherent in its subsequent development. For in this it develops, as its first warmth was. If this was chaste, its chastity is strengthened as it advances; but if unchaste, its unchastity increases as it advances, until it is stripped of all the chastity it had outwardly, but not inwardly, from the time of the engagement.