In this quote, the speaker describes a mental image of a building that exists only in their imagination, likening it to a drawing in their mind. The statement emphasizes the vividness of their mental visualization and how it resembles a real structure, even though it is purely conceptual.
The speaker also comments on the oddity of the sentence itself, suggesting that the idea of a "drawing in the brain" may sound strange to others. They invite the reader to reconsider this perception, implying that mental images can be as real and detailed as physical objects in our minds.