Why was Victor in such a good mood right before getting the upsetting letter from his father?

Victor recieves a letter from Elizabeth which reminds him how he longs for her company. He resolves to start his life again. Ending chapter 6 at the height of springtime, Shelley emphasizes Victor's wish to be reborn. The reader, however, already knows that such a wish is entirely in vain.

Victor's brother William dies