Direct Answer
Bercot’s sandstone analogy is meant to help you imagine “two realities” at once: outwardly it remains bread and wine, yet Christ can truly be present in them. If the analogy feels forced, Bercot would likely say the discomfort may reveal a deeper hesitation to believe God works through created matter without slipping into the superstitions he criticizes.
Support from Transcript:
Which concerns you more: treating bread and wine as nothing special, or treating them as magical? What would it look like to hold Bercot’s “real presence” idea with reverence but without superstition?