"'Bunter,' said Lord Peter, as the kitchen door closed behind them, 'do you know why I am doubtful about the success of those rat experiments?'

'Meaning Dr Hartman's, my lord?'

'Yes. Dr Hartman has a theory. In any investigation, my Bunter, it is most damnably dangerous to have a theory.'

'I have heard you say so, my lord.'

'Confound you - you know it as well as I do! What is wrong with the doctor's theories, Bunter?'

'You wish me to reply, my lord, that he only sees the facts which fit into the theory.'

'Thought-reader!' exclaimed Lord Peter bitterly.

'And that he supplies them to the police, my lord.'

'Hush!' said Peter, as the doctor returned.

from The Vindictive Story of the Footsteps that Ran by Dorothy L. Sayers