The cup (of wine) is one. The aspirants to drink from it (the Lover and the Beloved) are two. (That would imply dualism). That is not what love approves. How can those who dabble in the contest of figures maintain separate individuality of the Creator and the creatures and believe in multiplicity, attain to union with Allah? Just see how this individualism has come in the way of their union with Allah.
1) The story of the lover who came to his friend’s house and sought admittance is relevant. “Who is there” “It is I” “Then begone”, after a year the lover returned and being asked the same question replied “It is thou that art at the door” whereupon his friend received him saying “there is no room for two ‘l’s’ in one house. (Diwan-e-Shams Tabrez).
2) How can people think of union of the two when inherently they are one? Whoso through ignorance assigns them duality, he infact denies the other (i.e. Allah) . (Hazrat Zunoon of Egypt).
3) The first stage of union with Allah is in self-abnegation. Similarly the first stage of separation from Him lies in cooperation with nafs (Samnun)
چندا برو ایں رہ کہ دوئی برخیزد،
گرہست دوئی ز رہبر روی برخیزد،
(Khayyam)
Walk you to the place where duals cannot be. The twains you see, by plying further plea; You cannot be the Lord; but if you try, you reach where you are nought and all is He
تو او نہ شوی ولی اگر جہد کنی،
جائے برسی کہ از تو توئی برخیزد
(Roomi)
The river water keeps afloat on itself a corpse. If it had him alive the water would have sunk it

One cup! Two to drink! Love prohibits it,
Can the calculating ones come close to love?
Engrossed in their own being union to them cannot come.

One cup and two aspirants, is not the way of love,
How they be near the beloved who drink by counting cups,
See, the egocentrics are deprived of union with beloved.