The observer of the soul cannot penetrate into the soul, but there doubtless is a margin where he comes into contact with it. Recognition of this contact is the fact that even the soul does not know of itself. Hence it must remain unknown. That would be sad only if there were anything apart from the soul, but there is nothing else.
Science is about finding ever better approximations rather than pretending you have already found ultimate truth.
A casual stroll through the lunatic asylum shows that faith does not prove anything.
The concept of "mental health" in our society is defined largely by the extent to which an individual behaves in accord with the needs of the system and does so without showing signs of stress.