"I have learned not to think little of any one's belief, no matter how strange it may be. I have tried to keep an open mind." (Chapter 14)
Van Helsing identifies the one quality that has enabled him to gain the wisdom to counter the Count's evil: an open mind. It is the one quality that men such as Harker and Seward, whose narrowly rational viewpoint makes them deny the Count's alternative reality, manifestly lack. This lack, in turn, makes them vulnerable to the Count's attacks, since they cannot effectively oppose what they do not believe exists.