We saw, this day, Dundee and Aberbrothick, the last of which Dr Johnson has celebrated in his Journey. Upon the road we talked of the Roman Catholick faith. He mentioned (I think) Tillotson’s argument against transubstantiation; ‘That we are as sure we see bread and wine only, as that we read in the Bible the text on which that false doctrine is founded. We have only the evidence of our senses for both. If,’ he added, ‘God had never spoken figuratively, we might hold that he speaks literally, when he says, “This is my body”.’ BOSWELL. ‘But what do you say, sir, to the ancient and continued tradition of the Church upon this point?’ JOHNSON. ‘Tradition, sir, has no place, where the Scriptures are plain; and tradition cannot persuade a man into a belief of transubstantiation. Able men, indeed, have said they believed it.’
This is an awful subject. I did not then press Dr Johnson upon it; nor shall I now enter upon a disquisition concerning the import of those words uttered by our Saviour, which had such an effect upon many disciples, that they ‘went back, and walked no more with him’. The Catechism and solemn office for Communion, in the Church of England, maintain a mysterious belief in more than a mere commemoration of the death of Christ, by partaking of the elements of bread and wine.
[James Boswell, Journal of a Tour to the Hebrides, entry for 20 August]
By 'awful', of course, Boswell means 'a matter of awe or reverence'; and 'mysterious' means 'pertaining to a mystery, i.e., a truth exceeding natural reason alone'.