। ॥ ५८ ॥
In plain words
He looks at another man's wife, and the look is hungry; then he builds the whole daydream around her. He knew from the start she would never be his — and so, for nothing at all, the man takes on the full weight of the sin.
Close to the Sanskrit
He looks, with desire, at another's young woman; and he even makes a mind-chariot of her. Having known indeed the non-attainment of her, in vain the man becomes a partaker of exceeding sin.