We say the eye sees, the ear hears, the tongue speaks, the understanding reasons, the memory remembers, the will loves: but still we know well that it is the man, to speak properly, who by divers faculties and different organs works all this variety of operations. Man also then it is who by the affective faculty named the will tends to and pleases himself in good, and who has for it that great affinity which is the source and origin of love. Now they have made a mistake who have believed that resemblance is the only affinity which produces love. For who knows not that the most sensible old men tenderly and dearly love little children, and are reciprocally loved by them; that the wise love the ignorant, provided they are docile, and the sick their physicians. And if we may draw any argument from the image of love which is found in things without sense, what resemblance can draw the iron towards the loadstone? Has not one loadstone more resemblance with another or with another stone, than with iron which is of a totally different species? And though some, to reduce all affinities to resemblance, assure us that iron draws iron and the loadstone the loadstone, yet they are unable to explain why the loadstone draws iron more powerfully than iron does iron itself. But I pray you what similitude is there between lime and water? or between water and a sponge? and yet both of them drink water with a quenchless desire, testifying an excessive insensible love towards it. Now it is the same in human love; for sometimes it takes more strongly amongst persons of contrary qualities, than among those who are very like. The affinity then which causes love does not always consist in resemblance, but in the proportion, relation or correspondence between the lover and the thing loved. For thus it is not resemblance which makes the doctor dear to the sick man, but a correspondence of the one's necessity with the other's sufficiency, in that the one can afford the assistance which the other stands in need of: as again the doctor loves the sick man, and the master his apprentice because they can exercise their powers on them. The old man loves children, not by sympathy, but because the great simplicity, feebleness and tenderness of the one exalts and makes more apparent the prudence and stability of the other, and this dissimilitude is agreeable. On the other hand, children love old men because they see them busy and careful about them, and by secret instinct they perceive they have need of their direction. Musical concord consists in a kind of discord, in which unlike voices correspond, making up altogether one single multiplex proportion, as the unlikeness of precious stones and flowers makes the agreeable composition of enamel and diapry. Thus love is not caused always by resemblance and sympathy, but by correspondence and proportion, which consists in this that by the union of one thing to another they mutually receive one another's perfection, and so become better. The head certainly does not resemble the body, nor the hand the arm, yet they have such a correspondence and join so naturally together that by their conjunction they excellently perfect one the other. Wherefore, if these parts had each one a distinct soul they would have a perfect mutual love, not by resemblance, for they have none, but by their correspondence towards a mutual perfection. For this cause the melancholy and the joyous, the sour and the sweet, have often a correspondence of affection, by reason of the mutual impressions which they receive one of another by which their humours are reciprocally moderated.
But when this mutual correspondence is joined with resemblance, love without doubt is engendered much more efficaciously; for resemblance being the true image of unity, when two like things are united by a proportion to the same end it seems rather to be unity than union.
The affinity then of the lover and the thing loved is the first source of love, and this affinity consists in correspondence, which is nothing else than a mutual relation, which makes things apt to unite in order to communicate to one another some perfection. But this will be understood better in the progress of our discourse.