Mark Twain said this quote

When we set about accounting for a Napoleon or a Shakespeare or a Raphael or a Wagner or an Edison or other extraordinary person, we understand that the measure of his talent will not explain the whole result, nor even the largest part of it; no, it is the atmosphere in which the talent was cradled that explains; it is the training it received while it grew, the nurture it got from reading, study, example, the encouragement it gathered from self-recognition and recognition from the outside at each stage of its development: when we know all these details, then we know why the man was ready when his opportunity came.