The art of publicity is a black art; but it has come to stay, and every year adds to its potency.

The art of publicity is a black art; but it has come to stay, and every year adds to its potency.

宣传艺术是一门黑色艺术;但是它已经存在，并且每年都在增强它的效力。

-- Learned Hand 学过的手