The idiom 精疲力尽 (jīng pí lì jìn) is formed through a parallel and symmetrical structure common in classical Chinese, where two complementary phrases are combined to create a more emphatic meaning. The first half, 精疲, translates to "spirit exhausted", referring to mental or vital energy depletion, while the second half, 力尽, means "strength used up", indicating physical fatigue. Together, they form a compound that vividly conveys a state of total and utter exhaustion, where both one's mental vigor and physical power are completely drained.