Calculating Life

Weber begins "Science as a Vocation" by describing the difficulties and uncertainties of becoming a successful lecturer. He believes such a goal is a "matter of luck" and claims that "chance, rather than ability, plays an important role" (4). Weber states that chance is such a strong, deciding factor, not because of "defects of collective decision-making as a part of the selection process," but because in order to have a vocation as a scholar, one must not only be an apt scholar, but also an apt teacher, and he believes the possession of these two talents is an "utter gamble."
 Weber also explains the significance of inspiration. He affirms that inspiration does not abolish the need for work, and work cannot take the place of inspiration or force its existence, any more than passion can; but together, work and passion can create an idea (9). I viewed this as something positive, and agreed that ideas flourish when they're thought of in comfortable, relaxing environment. However, he reaffirms the presence of chance, and states "However that may be, the scholar must resign himself to the element of chance that is involved in every kind of scientific endeavor" (9).
Focusing on the significance of chance, Weber then switches to calculation and asserts that "we are not ruled by mysterious, unpredictable forces, but that, on the contrary, we can in principle control everything by means of calculation" (13). This idea confuses me, because if we can control, and calculate the things in our lives, why can't these aspiring lecturers calculate or account for the attributes that would make them successful? Is the calculations Weber speaks about purely scientific calculations such as those found in a Physics or Chemistry textbook, or could there be a way to calculate/systematically influence other areas of life?