小心谨慎 (xiǎo xīn jǐn shèn) — careful and cautious; prudent; circumspect

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

The shape of 小 comes from three small dots, later elongated into its strokes; the apparent parts 八 and 丨 are a later way of seeing it.

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

The shape of 心 comes from a drawing of a heart, now highly stylized.

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 謹; 谨 is its simplified writing.

The traditional form 謹 has 言, speech, beside 堇, which gives the sound; the whole character means to speak cautiously. The simplified 谨 is a shorthand.

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

In 慎, the left part 心 points to the mind or feeling, while the right part 真 supplies the sound.