Vaisesika Sūtra 3.1.20

प्रवृत्तिनिवृत्तिश्च प्रत्यगात्मनि दृष्टे परत्र लिङ्गम् ॥२०॥

pravṛtti-nivṛttiś ca pratyag-ātmani dṛṣṭe paratra liṅgam ॥20॥

[प्रवृत्तिः (pravṛttiḥ) - engagement or action; निवृत्तिः (nivṛttiḥ) - withdrawal or cessation; च (ca) - and; प्रत्यगात्मनि (pratyag-ātmani) - in the inner ātma; दृष्टे (dṛṣṭe) - when observed; परत्र (paratra) - in another (or elsewhere); लिङ्गम् (liṅgam) - is an indication (sign).]

Drive to act and withdrawal, when observed in the inner ātma, are indications of another.