It is just as that dear, good Professor Van Helsing said: he is true grit, and he improves under strain that would kill a weaker nature.
– Bram Stoker
Dracula, Chapter 17. As Jonathan is leaving for Whitby, Mina is comforted by what Van Helsing said about her husband. Having once found himself a prisoner of Dracula in Transylvania, she feels that Jonathan is now more experienced and determined in the fight to track down the Count and destroy him.