By all accounts Noach was a Tzadik. Yet he didnt go into the teivah until the water forced him in. Rashi tells us the reason was that Noach Believed and he didnt believe. Whilst he knew that Hashem was going to bring a mabul, he still doubted it. What seems perplexing is that Hashem spoke to Noach telling him there would be a flood. Not only that, but Noach had spent the last 120 years building a teivah for the flood. How was it possible that he didn't believe that Hashem was actually going to bring the flood?

Through this Shmuz we are introduced to one of the most fundamental concepts in belief, and why in fact true faith is so difficult for us.