Theory should not advance beyond the facts

In general, observation yields facts and deduction yields theories. The appropriate balance of observation and deduction involves an appropriate relationship between fact and theory, Throughout the canon, I advocate time and again that theory should not outrace fact:

I have no data yet. It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts [SCAN].
We approached the case, you remember, with an absolutely blank mind, which is always an advantage. We had formed no theories- We were simply there to observe and to draw inferences from our observations [CARD].
Now I make a point of never having any prejudices and of following docilely wherever fact may lead me --- [REIG].
It is a capital mistake to theorize in advance of the facts [SECO].
No data yet --- It is a capital mistake to theorize before you have all the evidence. It biases the judgment [STUD].
The temptation to form premature theories upon insufficient data is the bane of our profession [VALL].
Still, it is an error to argue in front of your data. You find yourself insensibly twisting them around to fit your theories [WIST].