Maurice Nicoll on Self-Observation

Now let me speak about the idea of self-observation more fully. It is not simply an end in itself: it is a means, not an end.
What is it a means to? I said just now that outer attention increases our consciousness of outer objects and that inner attention increases our consciousness of inner objects.
What is an inner object? A thought is an inner object. A feeling is an inner object. If you observe a thought or a feeling - and they are quite different and arise from different centres - you will realize that it is something in you, but not you.
When you do not observe your inner life it is merged with you and you are merged with it and everything lies in darkness. In this darkness, one is much victimized and set upon. It is therefore a good thing to let a ray of light in. This is self-observation.
We become more and more conscious of what is not us. If you take your thoughts and feelings as yourself - that is, as I - if you say ′I′ to them - you are inwardly in the greatest confusion and darkness. It is a long journey, getting rid of what is not us - what is not I.
At first you find it difficult to say to nearly all thoughts, feelings, sensations: "This is not I". On the contrary, you will say: "But this is I." No, it is not, and the fact that you can observe it proves it.

(Maurice Nicoll in Psychological Commentaries, vol.3 page 1143)