"He who listens to his body, knows when he needs rest."
Translation:Wer auf seinen eigenen Körper hört, weiß, wann er Ruhe braucht.
I thought the w- joiner words (e.g. wessen, wer, wem), as in other cases, are used in questions when the person(s) referred to is/are unknown. Therefore, I used the d- joiner word here 'der', and wrote, "Er, der auf seinen Körper hört, weiß, wann er Ruhe braucht." Is this impossible? or is it rather that such a formulation is avoided and in such cases (proverbs, for example) the ambiguous wer is used as subject....? thanks for any help.