He had an amazing ability to get you to suspend disbelief even as he self-consciously mixed in layers from elsewhere. I’m thinking of how he could have John Keats in his sci-fi story that mirrors the Canterbury Tales, or the whole Iliad, and you totally buy it.
If I had known the plot of these stories before I began I wouldn’t have because I would have thought it impossible for him to pull off the conceit, but he did.