The primary meaning of advent is "arrival," from the root advenire, "to come to"; in French, avenir, meaning "future." Like the word "adventure," which shares the same root, "advent" denotes a susceptibility to happenings whose unpredictability exceeds contingency: happenings that are "advenient," that is to say, additional, superadded, motivated rather than merely causal, but motivated by some force that is independent of the person (or era) to whom the arrival occurs.
See, for example, Partridge, which derives advent from the verb "to advene" and the adjective "advenient," "whence advenience, whence advent, whence Advent."
Johnson argues that in the case of both the many benefices and the taking of the life of the guilty person, the advenient
circumstances do not just "surround" the moral object of the act, but rather enter into the moral object of the act.