"More than once, I expect," Snape replied, without looking up from the paper - which he was happily marking down a grade for a rather egregious misspelling of a word he thought was meant to be precipitous. "It will require patience. Something that complex will involve multiple attempts." - And, to be very clear that that did not constitute an invitation, he raised his eyes briefly to where Nott was sitting across his desk. Patience was a virtue he was more than happy to encourage in the young, but he personally felt as though he exercised enough of it as it was. "Do not feel obligated to verbalize every one of them."