In his brilliant essay on ahavas Yisrael, the Beis HaLevi, Rav Yosef Dov Soloveitchik, beautifully explains the mitzvah of loving your fellow Jew. Who does the mitzvah apply to? When does it apply? What do I need to do to fulfill it properly? The Beis HaLevi also provides incentives to help us do the mitzvah in the best possible way.