Retired neurosurgeon Ben Carson is not backing down from a belief that drew widespread attention on Wednesday — that the Egyptian pyramids were built as grain silos, not elaborate tombs.

In a 1998 commencement speech at Andrews University unearthed by BuzzFeed, Carson pointed to hermetically sealed chambers as a sign the pyramids were used by Egyptians to store grain and food.

"My own personal theory is that Joseph built the pyramids to store grain," Carson said in the speech, referring to the biblical figure.

He added: "Now, all the archaeologists think that they were made for the pharaohs' graves. But, you know, it would have to be something awfully big — when you stop and think about it, and I don't think it'd just disappear over the course of time — to store that much grain."

Though he delivered the speech 17 years ago as part of a plea for graduates to "think big," Carson said Wednesday that he still stood by his belief.

"It is still my belief, yes," Carson said on Wednesday when asked about the speech by CBS News.

Various historians and archaeologists have discredited the theory, which carried some weight among ancient historians.

Carson has attracted attention for his more recent provocative comments on the campaign trail. Some of Carson's more controversial statements — for example, that he would not support a Muslim president, and that Adolf Hitler's regime benefited from gun control — have been well received among conservative voters.

According to a recent Bloomberg Politics/Des Moines Register poll released last month, 80% of likely Republican primary voters in Iowa said they agreed with his comparison of Obamacare to slavery. Seventy-seven percent, meanwhile, said they found his comments on gun control to be "attractive." And most potential Republican voters in Iowa said they would not vote for a Muslim president.