Where is the simple fact? Scientists have been seeking it in the two extremes, in the infinitely great and in the infinitely small. Biologists, for example, have been instinctively led to regard the cell as more interesting than the whole animal; and, since Poincaré's time, the protein molecule as more interesting than the cell. The outcome has shown the wisdom of this, since cells and molecules belonging to different organisms have been found to be more alike than the organisms themselves.
How then choose the interesting fact, the one that begins again and again? Method is precisely this choice of facts; it is needful then to be occupied first with creating a method; and many have been imagined, since none imposes itself. It's proper to begin with the regular facts, but after a rule is established beyond all doubt, the facts in conformity with it become dull because they no longer teach us anything new. Then it's the exception that becomes important. We seek not resemblances but differences, choose the most accentuated differences because they're the most striking and also the most instructive.
- What does the sentence in bold means?
And now that I had a vague idea what the sentence mean, what about the references:
- What is needful then to be occupied first with creating a method?
- What have been imagined?
- And none of what imposes itself?
Edit: Add a previous paragraph into the context, add 3 questions to elaborate more about the question.
Edit2: I had ponder on for several hours, and it occur to me that I might have misused 'reference'. I don't mean the reference of books, the 'reference' I am talking about here comes from Cohesion in English written by Halliday. And I had translate into three questions above. The second and the third may be ellipse, but for convenience I just call it reference because they all point to something in the text or in the register. I don't read the book thoroughly, and there may be error that I do not detect, but that's main idea of my question. Apology for my mistake.
Edit3: Well, what I am trying to said is I am new, and am trying my best as I can to ask a good question.
Please leave a comment before you downvote me, so I can understand where the problem is, and I will try my best to improve the question.
I don't know whether this question is a good question in your definition. But the question, especially the last three which underlie the first one, is important and valuable to me, and I'll try my best to get an answer. Thank you.