Depends on your style. In Hart's Rules, direct quotations have single quotation marks. Say this is your original text: Carr wrote, 'Together, they would bring "knowledge" to the unenlightened...
Use single quotation marks to indicate a quote within a quote.
If you're using a quote that contains a quote you'll need to surround the embedded quote with single quotation marks.
It's hard to explain so I'll give you an example: "I went to ask Danielle what her shift was and she said, 'I'm working on the second shift at 10:00'."