Knowledge ( Daat), which is the name of this sefira , is a euphemism for sexuality. Adam “knew” Eve…and they were as one flesh. This is because Daat 's capacity to integrate knowledge is so total that it can dissolve the existential chasm between knower and known, subject and object, heart and mind. It is no coincidence that the famous Tree of Knowledge is called after this sefira , for it is Daat (the capacity for integrated knowing) that shattered when Adam and Eve ate from it. As a consequence, we human beings experience an existential chasm between our heads and our hearts. It is easy to recognize truth with our brains; it is not at all easy to live by it .
If life is a spiritual path, our primary task is not the accumulation of facts, but the integration of truth so deeply into our flesh, that our instinctive and reflexive response to the world shifts accordingly. This is the Jewish definition of enlightenment.
Grapes are nearly synonymous with wine in mystical texts, and wine is a mind-altering substance. By extension, grapes denote the holy pleasure of expanding consciousness that comes from drinking wine (the physical equivalent of absorbing higher truths).