Maybe ‘the self-gratification of love’ or simply ‘the gratification of love’, or ‘the gratification intrinsic to love’. Remember, it needs to describe the motivation “for the joy set before him” as well as the motivation of the first responder or passing motorist.
@moderators – may we want to split a bunch of these to a new thread since there is a definite subthread here? Nah, since there are so many replies, maybe just leave it since the subthread appears to start all the way back at #14. It should be my mea culpa for not splitting it back then.