" The yin-yang sign is an appropriate symbol for complementarity, and was adopted as such by Niels Bohr. Its two aspects are equal, but different; each contains, and is contained within, the other. Perhaps not coincidentally, Niels Bohr was very happily married.

Once recognized, complimentarity is a wisdom we rediscover, and confirm, both in the physical world and beyond. It is a wisdom I embrace, and recommend to you. "

― Frank Wilczek , A Beautiful Question: Finding Nature's Deep Design