(1) The custom of observing birthdays of great men, especially of kings, was widespread in ancient times (see Ge 40:20 f, "the third day, which was Pharaoh's birthday," etc.; compare 2 Macc 6:7; and Herod. ix.110; in the New Testament, Mt 14:6; Mr 6:21, "Herod on his birthday made a supper to his lords," etc., i.e. Herod Antipas). Here we see the ancient custom reflected in two conspicuous instances centuries apart: (a) Pharaoh, on his birthday "made a feast unto all his servants," etc., and (b) Herod o n his birthday "made a supper to his lords, and the high captains," etc. The King James Version (Mt 14:6) has it "when Herod's birthday was kept," etc.
The correct text here (Tischendorf, Westcott-Hort) has a very peculiar construction, but without material difference of meaning. The locative case gives the time of the principal action, "danced on Herod's birthday, when it occurred." The construction is not unexampled (see Jelf, section 699). This need not be called "a case absolute," though it corresponds to the Latin ablative (locative) absolute; and the Greek genitive absolute is itself not really "absolute," i.e. it is not cut loose from the rest of the construction, but gives some event to which the principal action is referred, for the indication of its circumstances.
(2) The term "birthday" (ta genesia) was applied also to the anniversary of a king's accession to the throne (Edersheim); but Wieseler's argument that such is the case here is not conclusive. It is easy to suppose that when Herod's birthday approached he was sojourning at the castle of Macherus, accompanied by leading military and civil officials of his dominions (Mr 6:21). Petty ruler as he was, not properly "king" at all, he affected kingly ways (compare Es 5:3,6; 7:2).
(3) Genesia, which in Attic Greek means the commemoration of the dead, in later Greek is interchangeable with genethlia = "birthday celebrations"; and there is no good reason why the rendering of the King James Version and the Revised Version (British and American) here, "birthday," should not be right (See Swete on Mr 6:21, and HDB, under the word) For date of Christ's birth, etc., see JESUS CHRIST; CALENDAR, etc.
George B. Eager