an echo in hollow places

Having recently watched the film, I'm now reading Michael Ondaatje's "The English Patient" (Bloomsbury, 1992) and I was curious about the line at p.21 of the text: "For echo is the soul of the voice exciting itself in hollow places." It comes from a long poem by 18th century poet Christopher Smart, written during a spell of madness. Here is an excerpt containing the line Ondaatje used:

For applause or the clapping of the hands is the natural action of a man on the descent of the glory of God.

For EARTH which is an intelligence hath a voice and a propensity to speak in all her parts.

For ECHO is the soul of the voice exerting itself in hollow places.

For ECHO cannot act but when she can parry the adversary.

For ECHO is greatest in Churches and where she can assist in prayer.

For a good voice hath its Echo with it and it is attainable by much supplication.

For the VOICE is from the body and the spirit -- and is a body and a spirit.

For the prayers of good men are therefore visible to second-sighted persons.

from Christopher Smart: Jubilate Agno via pseudopodium.org

There is a curious resonance with the passage below from Elizabeth Lash, who simply happens to be the mother of the actor, Ralph Fiennes, who played the titular role in the movie.

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