穷理尽性 Origin — Chinese Character Wiki

qiónglǐjìnxìng

to explore the truth and nature of things

穷理窮理 qiónglǐ

to probe the nature of things

to investigate or trace the underlying principles of things to their very root
尽性盡性 jìnxìng

to fulfill one's nature

to fully develop or display one's innate nature or character; to give full play to the natural properties of things