Pharaoh was so impressed with Joseph's skillful interpretation of his dream that he appointed him viceroy of Egypt in order to enable him to implement his plan. After he was made viceroy, Joseph's former master, Potiphar, gave him his daughter in marriage. During the seven years of plenty, Joseph had two sons: Menasseh and Ephraim.
Joseph named his firstborn Menasseh...he named his second son Ephraim.
Bereishit 41:51-52
Living in exile requires us to use two apparently contradictory approaches toward the world at large: On the one hand, we must be constantly on guard against harmful influences; on the other hand, we must engage the outside world in order to influence it positively.
Clearly, influencing our environment is a greater accomplishment than merely maintaining our values. Nonetheless, maintaining our values must be taken care of first, for if we forget our roots we will no longer have anything to contribute to the world.
The two sons of Joseph, born and raised in Egypt, personified these two aspects of life in exile. Joseph names his firstborn Menasseh (meaning "[Exile] causes one to forget") in order not to forget his family and heritage. Joseph named his second son Ephraim ("he will be fruitful") in order to emphasize that our purpose in the world is to influence it positively.
From Kehot's
Daily Wisdom #1