good and evil are two faces of the same coin
Buddhist expression meaning that good and evil are not fundamentally separate; they are two aspects of the same reality.
In Zen teachings, there is the phrase 'good and evil are not two'.
A Buddhist term composed of 善悪 (good and evil) and 不二 (non-duality, not two). The exact historical derivation is uncertain, but it reflects the Mahayana concept of non-duality.