明哲保身

Contraction of a line from the Classic of Poetry:

既明且哲，以保其身。 [Pre-Classical Chinese, trad. and simp.]

From: The Classic of Poetry, c. 11^th – 7^th centuries BCE, translated based on James Legge's version

Jì míng qiě zhé, yǐ bǎo qí shēn. [Pinyin]

Intelligent is he and wise,
Protecting his own person.

明哲保身

1. to protect or defend oneself with wisdom and sound judgement
2. to protect oneself above all other considerations; to place one's own interests at the foremost

As chengyu, the connotation has gradually shifted away from the literal meaning. The second sense carries the connotation that protecting one's self-interest (保身 (bǎoshēn)) is the "wisdom" referred to by 明哲 (míngzhé), and its use implies indifference, lack of altruism, unwillingness to take risk, etc., all of which considered practices of the wisdom.