This is, indeed, involved in what has been said about the nature of the process.

Insight, as we have seen, though here classed with preservative cognition, occupies a kind of border-land between immediate knowledge or intuition and inference, shading off from the one to the other.

And in the very nature of the case the scope for error must be great.

Even overlooking human reticence, and, what is worse, human hypocrisy, the conditions of an accurate reading of others' minds are rarely realized.

If, as has been remarked by a good authority, one rarely meets, even among intelligent people, with a fairly accurate observer of external things, what shall be said as to the commonly claimed power of "intuitive insight" into other people's thoughts and feelings, as though it were a process above suspicion?
It is plain, indeed, on a little reflection, that, taking into account what is required in the way of large and varied experience (personal and social), a habit of careful introspection, as well as a habit of subtle discriminative attention to the external signs of mental life, and lastly, a freedom from prepossession and bias, only a very few can ever hope even to approximate to good readers of character.
And then we have to bear in mind that this large amount of error is apt to remain uncorrected.