A common mistake of beginners is the desire to understand everything completely right away. In real life understanding comes gradually, as one becomes accustomed to the new ideas. One of the difficulties of scientific research is that it is impossible to make progress without clear understanding, yet this understanding can come only from the work itself; every completed piece of research represents a victory over this contradiction.
This quote comes from the preface of one of my favorite books "Qualitative Methods in Quantum Theory" by a great practitioner of theoretical physics Arkady Migdal.