expression, nidan verb (lower class) with 'ru' ending (archaic)
what you believe in your heart is revealed in your face
Proverb meaning that one's inner thoughts and feelings naturally show on one's countenance. Archaic verb form あらわる (modern あらわれる).
As the proverb says, 'What you believe in your heart is revealed in your face,' his anxiety showed on his face.
Modern equivalent with the same meaning, using the modern verb 表れる instead of the archaic あらわる.
A Japanese rendering of the maxim 誠於中、形於外 in the Chinese classic 『大学』: what is sincere within takes visible form outwardly.