What makes Cupid's arrows stick?

Thomas Stuttaford in the London Times:

Cupid, the son of Venus, sharpened his arrows, too — in a similar way to that employed at the Fleggburgh surgery, though he used blood rather than oil on his grindstone. There is a legend, followed up by Shakespeare, that Cupid had two types of arrow: one gave rise to long-lasting, committed, so-called virtuous love, the other to lust. The arrows that led to lasting love were gold, which would have needed careful sharpening to penetrate and stay embedded.

The lovestruck person hit by a golden arrow would pass through the three stages leading to lasting commitment — lust, acceptance and attachment, and deep friendship. What could be more virtuous? Cupid’s other arrows were leaden: although they might strike their victim, they were unlikely to penetrate, let alone to remain embedded. Cupid’s leaden arrow gave rise to short-lived, lustful, sensual passion.

That there are different types of love, the virtuous and the lustful, the one lasting and the other transient, is accepted by neurophysiologists and psychologists. The brain and the hormonal endocrine system have been studied, as has the biochemical and radiological effect of the two types of arrow. Cupid’s arrows now are made neither of gold nor of lead, but by visual images and, above all, by a whiff of pheromones or scent.

More here.