"Shoshin" is the Zen Buddhism term for retaining the spirit of openness and lack of preconceptions of a beginner or novice. To not think of oneself as an expert, but to remain receptive and open to new learning and new experiences even when one achieves an advanced level of practice. Many consider this to be essential in subduing the ego, a fixed and conditioned state that we subconsciously and reflexively impose upon ourselves. By keeping the ego in check, and using the ego as a detached observer or advisor, we can achieve a more peaceful mental state and begin to integrate that peacefulness into our relationships with others.
This is an important concept in martial arts. While we are studying how to fight, and we know from childhood that fighting and violence are wrong, we are learning to become more peaceful within ourselves. It is very easy for someone to develop an inflated ego as higher rank is achieved. Keeping a beginner's mind helps to prevent this, and leaves the door open for new learning in addition to new ways of thinking about old ideas. There is always something new to discover.
Consider a kata, even a "beginner" kata. With experience and training, a beginner kata can be performed without really thinking about it very much. But try to imagine an opponent, what that opponent may or may not be doing against you, and how you react. Have you thought of everything? That is difficult. While some ideas may be more valid or appropriate than others, keeping your mind away from preconceptions helps to give a new perspective to your thinking.
