משך חכמה — אזכור עלייה לרגל סמוך לשמיטה

Q — Why does the Mechilta need to teach that the שלוש רגלים apply even in the שמיטה year — what הוה אמינא would suggest they don't?

A — The agricultural framing here (אביב, קציר, אסיף) suggests aliyah l'regel exists to acknowledge "לה' הארץ," like an אריס reporting to his master — in which case the entire שמיטה year (when working the land is forbidden) would be a continuous reminder and the regalim would be unnecessary. The chiddush is that the regalim are NOT primarily for that, but for דבקות in Hashem through דבקות in Klal Yisrael — and the three annual gatherings sustain a person spiritually all year, the way an "אבר המדולדל" remains part of the living body so long as it can rejoin.