Riesner's Messias Jesus

I am delighted to hear of Prof. Rainer Riesner's forthcoming book, Messias Jesus, for which more information can be found here.

He kindly sent me an interview with idea.de, which you can read below.

It ends with this citation: "Es ist historisch möglich zu wissen, wer Jesus war und was er wollte".
What do you think: is it possible? What does it mean for historians to know who someone is? I'm very much looking forward to reading this one as Rainer is not only a deeply learned scholar from whom I have learned much, but also a terrific person to know.