Another quote by a Nobel winning physicist. Niels Bohr was physicist who had big contributions to understanding atomic structure and quantum theory. Neils is also the person behind the bohr model, the atom model we learned in school. Bohr was also a philosopher, and thus we can understand his philosophical quote.
An expert is a person who has made all the mistakes that can be made in a very narrow field– Niels Bohr
In any particular field, we all start with no knowledge or skills at all. We acquire knowledge and skills with time.
With time we make mistakes and we learn from these mistakes, or the mistakes of others.
Hence the term expert, as someone that knows the field very well. But the narrower the field, the more knowledgeable the expert will be. Hence An expert is a person who has made all the mistakes that can be made in a very narrow field!