Harry Guntrip said this quote
“ Complaints of feeling cut off, shut off, out of touch, feeling apart or strange, of things being out of focus or unreal, of not feeling one with people, or of the point having gone out of life, interest flagging, things seeming futile and meaningless, all describe in various ways this state of mind. Patients usually call it 'depression', but it lacks the heavy, black, inner sense of brooding, of anger and of guilt, which are not difficult to discover in classic depression. Depression is really a more extraverted state of mind, which, while the patient is turning his aggression inwards against himself, is part of a struggle not to break out into overt angry and aggressive behaviour. The states described above are rather the 'schizoid states'. They are definitely introverted. Depression is object-relational. The schizoid person has renounced objects, even though he still needs them. ”