two wings to fly

If you want to become whole, let yourself be partial;
if you want to become straight, let yourself be crooked;
if you want to become full, let yourself be empty;
if you want to be reborn, let yourself die.

If you want to be given everything,
give everything up.

-- Tao Te Ching, The Book of the Way


This reminds me of:

God turns you from one feeling to another and teaches by means of opposites
so that you will have two wings to fly, not one.

-- Rumi


And apparently, these too:

And of everything we have created pairs; that you may receive instruction.

-- Al-Quran 51:49

Exalted is He who created everything in pairs -- from what the earth grows and from themselves and from that which they do not know.

-- Al-Quran 36:36