philosophy, clear
啠 centers on deep understanding and clarity of thought: philosophy and clear insight. The given meanings are closely linked, with philosophy representing systematic clear thinking.
啠 is a rare variant of 哲. 哲 combines 折 (break) and 口 (mouth), suggesting breaking through to clear speech or wisdom. 啠 replaces 折 with 斦 (two axes), which may reinforce the idea of cutting through to clarity, but the exact historical development is uncertain.
Two axes 斤斤 at the top cut through confusion, and the mouth 口 at the bottom speaks clear philosophy.
For テツ, imagine a philosopher named Tetsu using two axes to chop through unclear ideas: Tetsu -> テツ.