। ॥ ६४ ॥
In plain words
The seed of desire is saṅkalpa — the mind imagining a thing and settling on it. Desire is born from that seed and from nothing else. And just as no sprout comes up once the seed is destroyed, desire perishes the moment saṅkalpa is gone.
Close to the Sanskrit
Of desire the seed is saṅkalpa; from saṅkalpa alone it is born. Like the sprout when the seed has been destroyed, so, when that has been destroyed, it perishes.