[Note 16, Chapter Two, in print version]
John D. Rosenberg, "The Two Kingdoms of In Memoriam," Journal of English and Germanic Philology, 58 (1959), p. 238, quotes and comments upon the poet's remarks. He also argues that
The progression from death to life is again implicit in the reference to the 'spiritual rock,' from which Moses struck water in the desert and which Paul called the rock that 'was Christ,' — the same rock from which man partakes of the baptismal waters of rebirth and on which Tennyson bases his faith that we shall 'close with all we loved . . . soul in soul'" (p. 238).
Professor Rosenberg here refers to the Pauline interpretation of the stricken rock as a type of baptism, a reading of the image which does not seem to work as well in this case as the interpretation I have suggested.
Print version published 1980; web version 1998