When one analyzes the pre-conscious step to concepts, one always finds ideas which consist of 'symbolic images.' The first step to thinking is a painted vision of these inner pictures whose origin cannot be reduced only and firstly to the sensual perception but which are produced by an 'instinct to imagining' and which are re-produced by different individuals independently, i.e. collectively... But the archaic image is also the necessary predisposition and the source of a scientific attitude. To a total recognition belong also those images out of which have grown the rational concepts.

I have done a terrible thing, I have postulated a particle that cannot be detected.

The fact that the author thinks slowly is not serious, but the fact that he publishes faster than he thinks is inexcusable.

How can one avoid despondency if one thinks of the anomalous Zeeman effect?

The layman always means, when he says "reality" that he is speaking of something self-evidently known; whereas to me it seems the most important and exceedingly difficult task of our time is to work on the construction of a new idea of reality.

The natural scientist is concerned with a particular kind of phenomena ... he has to confine himself to that which is reproducible ... I do not claim that the reproducible by itself is more important than the unique. But I do claim that the unique exceeds the treatment by scientific method. Indeed it is the aim of this method to find and test natural laws.

From the point of view of logic, my report on 'Exclusion principle and quantum mechanics' has no conclusion. I believe that it will only be possible to write the conclusion if a theory will be established which will determine the value of the fine structure constant and will thus explain the atomistic structure of electricity, which is such an essential quality of all atomic sources of electric fields actually occurring in nature.