Charles Ellicott Commentary Luke 3:23

"And Jesus himself, when he began [to teach], was about thirty years of age, being the son (as was supposed) of Joseph, the [son] of Heli," — Luke 3:23 (ASV)

Began to be about thirty years of age.—At this age the Levites began their full work (Numbers 4:23; Numbers 4:30; Numbers 4:35), a kind of probationary period beginning at twenty-five (Numbers 8:24) or even, in later times, when their work was lighter, at twenty (1 Chronicles 23:27). No age was fixed for the beginning of the priesthood, nor for the prophet’s work; but it may fairly be inferred that thirty was regarded as the time when manhood reached its completeness, and we may therefore believe that our Lord waited in patient humility until that age had been attained before beginning the work of His public ministry.

Being (as was supposed) the son of Joseph.—We must here address the many questions that arise from a comparison of this genealogy with that in Matthew 1:0. It is a subject on which volumes have been written. Here, it will be enough to summarize the results of previous inquiries.