In reference to the Eucharist as a sacrifice, Communion under both kinds belongs at least to the integrity and essence, of the rite, and may not be omitted without violating the precept of Christ: "Do this in remembrance of me" (Luke 22:19). This is mentioned implicitly by the Council of Trent (Sess. XXI, c. i; XXII, c. i), and the General Instruction of the Roman Missal states that the people "should share the cup when it is permitted. Then, Communion is a clearer sign of sharing in the sacrifice that is actually being celebrated."
