Quite apart from its utility, the chin paten reminds the faithful of the mystery of the One who is present to us under the sacramental species of bread.
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Another reason to use the chin paten is that it subtly encourages the faithful to receive on the tongue, since the paten seems to have its use most properly in that configuration. The signal is transmitted that something special is occurring in reception on the tongue that reception on the hand rules out.
(Read full article by Peter Kwasniewski here.)