"Let me be accurate in everything, for though you and I have seen some strange things together, you may at the first think that I, Van Helsing, am mad. That the many horrors and the so long strain on nerves has at the last turn my brain"

In this quote, Van Helsing is stressing the relevance of precision in his words. He realizes that his experiences with the supernatural have actually been so odd as well as intense that his buddy might believe he has gone mad. He is asking his buddy to take his words seriously and also not dismiss them as the ramblings of a madman. Van Helsing understands that the horrors he has actually seen and also the stress on his nerves have actually taken a toll on him, however he is still established to be accurate in his words. He wants his friend to understand that his words are not the product of a mad mind, but instead the outcome of his experiences and also monitorings.