Imperfect understanding is often more dangerous than ignorance.

How awful it was, thought Tessa, remembering Fats the toddler, the way tiny ghosts of your living children haunted your heart; they could never know, and would hate it if they did, how their growing was a constant bereavement.

It is impossible to live without failing at something, unless you live so cautiously that you might has well not have lived at all, in which case you have failed by default.

I knew I could do it all this time,” said Harry, “Because I'd already done it... does that make sense?

And Hermione was struggling to her feet in the wreckage, and three red-headed men were grouped on the ground where the wall had blasted apart. Harry grabbed Hermione's hand as they staggered and stumbled over stone and wood. 'No - no - no!' someone was shouting. 'No! Fred! No!' And Percy was shaking his brother, and Ron was kneeling beside them, and Fred's eyes stared without seeing, the ghost of his last laugh still etched upon his face.

Professor Snape was forcing them to research antidotes. They took this one seriously, as he had hinted that he might be poisoning one of them before Christmas to see if their antidote worked.

You saved Dad's life. If anyone's got the right to eavesdrop on him, it's you.