Theory versus Practice

I discovered this excerpt from Sir Athur Conan Doyle's "The Yellow Face" the other day:

Holmes: What do you think of my theory?

Watson: It’s all surmise.

Holmes: But at least it covers all the facts. When new facts come to our knowledge which cannot be covered by it, it will be time enough to reconsider it.

Exactly, my dear Holmes, exactly! How pertinent to my current PhD situation this is!!!!