Πρωτότοκον.  The word occurs in Heb. i. 6, which had been read in the Lesson before this Lecture.  The exact dogmatic sense of the word is carefully explained by Athanasius (c. Arian. Or. ii. 62):  “The same cannot be both Only-begotten and Firstborn, except in different relations;—that is, Only-begotten, because of His generation from the father, as has been said; and First-born, because of His condescension to the creation, and His making the many His brethren.”  See Mr. Robertson’s discussion of the word πρωτότοκος (Athan. p. 344, in this series), and Bp. Bull (Def. Fid. Nic. iii. 5–8).