Direct answer
Objectives follow journal display order. Some depend on your choices; follow the active objective in the game.
Result
It was a warm summer evening... or perhaps a cool yet sunny morning? The weather and time are of no import, what matters is that day Geralt received a letter full of kind words from his beloved Triss, who informed him about a most unusual discovery she had recently made. In some old manuscripts she'd found mention of research conducted by a Professor Moreau on witcher mutations. It seemed this professor's workshop could be found in Toussaint. Geralt, realizing the importance of this discovery, decided to find this laboratory. The first step would be to find the professor's journal which, according to Triss, had been buried with him.
