殫精極慮

to exhaust one's thoughts and ingenuity (idiom); to think sth through thoroughly / to rack one's brains / to leave no stone unturned

entirely / to exhaust

essence / extract / vitality / energy / semen / sperm / mythical goblin spirit / highly perfected / elite / the pick of sth / proficient (refined ability) / extremely (fine) / selected rice (archaic)

extremely / pole (geography, physics) / utmost / top

to think over / to consider / anxiety