Perhaps your interlocutor was referring to "Joseph and his Brothers", printed in The Rav Speaks, where R. Soloveitchik says (my emphasis):
The Biblical Joseph relates: "and behold the sun and the moon and the eleven stars bow down to me" (Gen. 37:9) — there is secular culture, great and powerful technology creating wonders and changing the foundations of our life. Even if it is true that in Canaan we can get along without it — this secular culture entails destructive elements, many negative and perverse aspects; it may be a blessing and a curse simultaneously, and thus as long as one can live without it, so much the better for the spirit — finally we will have to relate to it. The confrontation will not take place in Canaan, however, where life flows serenely, but in a new and alien land where the tempo of life is greatly accelerated and fundamental changes occur daily.
I don't know that this would be termed R. Soloveitchik's "foundational essay on Modern Orthodoxy", though.