前车之鉴 (qián chē zhī jiàn) — lessons learned from previous mistakes (one's own or others'); a cautionary example

Two or more meaningful parts placed together so that their meanings combine into a new one.

In the older form of 前, 止 (foot) and 舟 (boat) showed a foot on a boat moving forward; in the current 前 those parts are shortened.

A drawing of the thing itself, worn down over three thousand years into a few strokes.

This origin belongs to the traditional form 車; 车 is its simplified writing.

The traditional form 車 was drawn as a carriage seen from above, with wheels on both sides and a shaft at the front; the simplified 车 is a later shorthand.

Two or more meaningful parts placed together so that their meanings combine into a new one.

The shape pairs 止, a foot, with 一, a beginning place, and means to go.

Most characters — around four in five — are built this way: one part hints at the meaning, the other at the pronunciation.

This origin belongs to the traditional form 鑑; 鉴 is its simplified writing.

The traditional form 鑑 pairs 金, showing metal, with 監 for sound; the simplified 鉴 is a later abbreviation, not the source of this shape.