I once read that when we look at our tzitzit we're reminded of our obligation to keep all 613 commandments (and possibly more). Because it's written: 'And you shall see it and remember all the mitzvot (of) HaShem and you shall do them (Bamidbar 15:39)'. The Chazon Ish relates that fulfilling the mitzvah of tzitzit binds you eternally to the entire Torah.
But how can one really do all the mitzvot or keep the entire Torah? Aren't some mitzvot only applicable to men, women, priest, judges, kings etc?
R' Elazar Kallir z"l explains that When the Jewish people are united as one body, with one heart, then that body can observe the entire Torah. Are there more commentaries that teach this principle?