A reminder of Christ's presence...
The tabernacle for Eucharistic reservation is a reminder of Christ's presence that comes about in the sacrifice of the Mass. But it is also a reminder of the brothers and sisters we must cherish and charity, since it was in fulfillment of the sacramental ministry received from Christ that the church first began to reserve the Eucharist for the sake of the sick and the dying. In our churches adoration has always been offered to the reserved sacrament, the bread which comes down from heaven. - Book of Blessings, no. 1192.