One of the other debated issues in the Lord's Supper, in addition to the question of presence, is that of fencing the table. Who may participate? What does it mean to eat and drink unworthily? Who is worthy? Who is unworthy? Calvin takes up these questions in 4.17.40 - 42. He also deals with the question of how it is to be administered in terms of the liturgy of the communion service (4.17.43). Finally, he tackles the question of frequency (4.17.44). All of these questions are worthy of book-length treatments in and of themselves.
Calvin continues his discussion of the errant Roman Catholic view of the sacrament of the Lord's Supper by prattling on about one of his favorite subjects to rail upon: superstition and idolatry. The two, for Calvin, go together like ham and eggs. These practices, in this particular instance the piled on traditions of the adoration of "consecrated host," are repugnant to Calvin because they are extra-biblical (actually, he makes the case that they are anti-biblical) and injurious to the Christian life. How quickly the church can lose its way; how quickly we can lose our way.
In an oft-quoted passage, Charles Spurgeon reflects on the nature of his calling as a pastor:
How has this affected our nation and churches?
The Korean Revival and Following Persecution
Hamu Lujonza Kaddu Mukasa and the Early Church in Uganda
From Mukasa to Hamu