Seneca, De beneficiis 2.18.1-2
Any duty involving two people makes equal demands on them both. Having examined what a father should be like, you will know that just as much work remains in order to make out what a son should be like. If a husband has a role to play, the wife has no less of one. (2) The reciprocity in making demands and fulfilling them requires a rule which applies to both alike - and that, as Hecatonn says, is a difficult matter. Moral goodness, indeed anything approaching moral goodness, is always uphil1. It requires not merely action, but rational action. Reason must be our guide throughout our life; all things, from the smallest to the greatest, must be performed on its instructions; gifts must be given in whatever manner reason suggests.
Seneca, Moral and Political Essays. Eds. John M. Cooper and J. F. Procopé (Cambridge: CUP, 1995), 226.