Manasseh in Fausset's Bible Dictionary

("causing to forget".) Joseph's firstborn by Asenath, whose birth "made him forget all his toil and all (the sorrow he endured through) his father's house" (Genesis 41:51). Jacob adopted them as his own, though "horn in Egypt" and by an alien to Israel (Genesis 48:5; Genesis 48:9); "as Reuben and Simeon they shall be mine," i.e. patriarchal heads of tribes, as Jacob's immediate sons were; Manasseh and Ephraim gave their names to separate tribes. Joseph had the portion of the firstborn by having the double portion, i.e. two tribal divisions assigned to his sons (1 Chronicles 5:1-2; compare Deuteronomy 21:17). When Joseph took Ephraim in his right toward Israel's left hand, and Manasseh in his left toward Israel's right hand, Israel put his right upon Ephraim the younger, and his left upon Manasseh wittingly, notwithstanding Joseph's remonstrance. Their name should be a formula of blessing, "God make thee as Ephraim and Manasseh," and they should "grow as fish do increase" (a natural image near the fish abounding Nile): Genesis 48:16; Genesis 48:20...