I must now add that active illusion may be due to causes similar to those which we have seen to operate in the sphere of illusory perception and introspection.

That is to say, there may be a disposition, permanent or temporary, to ascribe a certain kind of feeling to others in accordance with our wishes, fears, and so on.
To give an illustration of the permanent causes, it is well known that a conceited man will be disposed to attribute admiration of himself to others.

On the other hand, a shy, timid person will be prone to read into other minds the opposite kind of feeling.
Coming to temporary forces, we find that any expectation to meet with a particular kind of mental trait in a new acquaintance will dispose the observer hastily and erroneously to attribute corresponding feelings to the person.

And if this expectation springs out of a present feeling, the bias to illusory insight is still more powerful.

For example, a child that fears its parent's displeasure will be prone to misinterpret the parent's words and actions, colouring them according to its fears.
So an angry man, strongly desirous of making out that a person has injured him, will be disposed to see signs of conscious guilt in this person's looks or words.