From Wikipedia

Introverted feeling is “very hard to elucidate since so little of it is openly displayed.” Jung writes of feeling in introverted feelers: “[Introverted feeling] is continually seeking an image which has no existence in reality, but which it has seen in a kind of vision. It glides over all objects that do not fit in with its aim. It strives after inner intensity, for which the objects serve at most as a stimulus. The depth of this feeling can only be guessed—it can never be clearly grasped. It makes people silent and difficult to access; it shrinks back like a violet from the brute nature of the object in order to fill the depths of the subject. It comes out with negative judgments or assumes an air of profound indifference as a means of defence.”