If we accept that love is the feeling that involves attributing value to something, an unsettling idea presents itself: we seem to have uncovered something we cannot quite name—perhaps a condition of love or a law of love: 'To love something, you must attribute a real value to it'. Or: 'Do you want to love this thing? Then attribute value to it'.
This type of imperative—neither hypothetical nor categorical but rather 'erotic' (derived from Eros)—puzzles us because we are unsure what status to assign to it.

In the first place, we are uncertain whether it is truly an imperative. The inference takes the following form: 'X is Y. Therefore, for X to exist, Y must exist'. Here, the verb 'must' implies a factual necessity rather than a legal or moral one. It is used in the same way as in the peculiar statement: 'Man is rational. Therefore, man must be rational'. On closer inspection, it does not appear to be an imperative at all, but rather a reformulation of a fact or an essential proposition expressed in misleadingly imperative terms.

Secondly, the idea that 'to love, we must assign value' does not appear to be a law imposed from some external realm—such as legal or moral authority governing love from above. It seems, rather, to represent a necessity arising from love itself, one that enables love to occur—a quite different matter.
We are not dealing with a moral imperative that seeks to 'discipline' love through notions of right or duty; in short, this is not a 'law of love'. We are, rather, addressing an essential condition for the concept of love to have any meaning. Once a content of meaning Y forms part of the meaning of X, Y must exist for X to exist—this is the type of necessity at issue here. Since love is the attribution of value to the beloved object, attributing value to the object we claim to love is a condition for that love to qualify as genuine.

Finally, this is not a typical hypothetical imperative determining which means must be chosen to achieve a given end, since there is no means-ends relationship between attributing value and love. There is, rather, an identity of essence: we do not attribute value in order to love; to attribute value is, in itself, to love.