An excerpt from A Theological Introduction to the Thirty-Nine Articles of the Church of England by E. J. Bicknell, 3rd. ed. revised by H. J. Carpenter. pp. 400-403. First published 1919, this edition 1955. This article represents the views of the author and not necessarily those of Whitehall or any of its contributors. :)
The Sacrament of the Lord's Supper was not by Christ's ordinance reserved, carried about, lifted up or worshipped. This last section of the Article is carefully worded. It is based on a sound and intelligible principle. The Holy Communion was given to us by Christ for a definite purpose. We can only be secure of its blessings so long as we respect the limits of that purpose. [Bicknell goes on to explain how Christ's presence in the Eucharist is a spiritual, and therefore uncontrollable, presence, and that we can't predict with certainty where or when He will be present in the Eucharistic elements except in the context of their use in the Lord's Supper.] We cannot be certain that that Presence abides when we use the consecrated bread and wine for a new and entirely different purpose, a purpose not ordained by Christ, but prompted by the fallible logic of human devotion. . . . We cannot, as it were, bind Him to earth by our treatment of the elements. Such thoughts lie behind the very cautious statements of the Article. The practices mentioned are not condemned as sinful. No anathema is leveled at those who retain them. All that is asserted is that they are precarious, as going outside the ordinance of Christ. . . .
Reservation purely for the communion of the sick or absent is thoroughly primitive and natural. It is in full accord with the spirit of Scripture and the revealed purpose of Christ and was the custom of the primitive church. . . . [There follows a long list of patristic sources that mention reservation for this reason.] In the second Prayer-Book this permission [to reserve for the sick or absent, so long as they communicated on the same day as the congregation] was withdrawn: there was a very real danger of conveying the sacrament away and using it for superstitious purposes. In 1662 the present rubric was added enjoining the consumption in church of all the consecrated elements at the close of the service. The primary object of this was to forbid not reservation but the irreverent carrying of the elements out of church for ordinary consumption, which the Puritans were quite capable of doing. But indirectly the rubric forbids all reservation . . . This is a real loss. . . .
The Article is aimed at reservation when practiced not only for purposes of communion, but in order to provide a localized object of worship. This is a comparatively modern and entirely distinct practice. It is a use of the sacrament that diverges widely from the declared intention of Christ. It arose in the dark ages and received a great impulse through the assertion of Transubstantiation. . . .
Carrying about the Host in procession is only an extension of the same practice. . . .
The lifting or elevation of the Host after consecration in order to be adored by the people . . . Is on a level with the previous practices. This elevation must not be confused with the manual acts during the prayer of consecration, when the priest solemnly reproduces the action of Christ at the Last Supper and takes up the bread and the cup. . . .
If Christ is present in the Eucharist, most certainly He is then as always to be adored. But this, as we have seen, is quite different from adoration of the Blessed Sacrament divorced from Eucharistic worship. We have no ground for believing that He gave us the Eucharist in order to dwell among us to-day by an abiding external presence as during His earthly life or to afford a visible object of adoration. Nor, again, are we justified in that absolute identification of our Lord with the outward sign that is implied in modern Roman devotions.
Finally, let us gladly admit that in these practices as allowed by the Church of Rome to-day we do find the expression of very deep and real devotion to our Lord. But we maintain that that devotion is purchased at a great cost.