Here comes a compilation of quotes by Roberto Assagioli about the Middle unconscious
“The Middle Subconscious
This is formed of psychological elements similar to those of our waking consciousness and easily accessible to it. This inner region is the seat of the elaboration of our experiences, of the preparation of our future expression and of our average mental and imaginative activities.” (Psychoanalysis and Psychosynthesis)
“This is formed of psychological elements similar to those of our waking consciousness and easily accessible to it. In this inner region our various experiences are assimilated, our ordinary mental and imaginative activities are elaborated and developed in a sort of psychological gestation before their birth into the light of consciousness.” Psychosynthesis, 1965, p. 17
“Is formed by psychological elements of a similar nature to those of wakeful consciousness and easily accessible to it. It includes the elaboration of the experiences made, the preparation of future activities, much of the intellectual work (theoretical and practical), imaginative and artistic creation of average degree and value. It is a kind of “psychological gestation” that precedes the emergence in the field of consciousness.” (The Mystery of the “I”, Assagioli Archive)
“Psychoanalysis generally stops here [Lower unconscious]; but this limitation is not justified. The regions of the middle and higher unconscious should likewise be explored. In that way we shall discover in ourselves hitherto unknown abilities, our true vocations, our higher potentialities which seek to express themselves, but which we often repel and repress through lack of understanding, through prejudice or fear. We shall also discover the immense reserve of undifferentiated psychic energy latent in every one of us; that is, the plastic part of our unconscious which lies at our disposal, empowering us with an unlimited capacity to learn and to create.” Psychosynthesis, 1965, p. 22
“The middle zone is the abode of the psychic elements and activities similar to those of waking consciousness and easily accessible to it. It is the pre-conscious, and in it occur the elaboration of experience and the preparation of future activities.” (Psychosynthesis Medicine and Bio-Psychosynthesis)
The Middle Unconscious; from the article by Kenneth Sørensen, The developmental theory of psychosynthesis
The contents of the Middle Unconscious (2) are much like those of the waking consciousness of a relatively rational and educated human being, young or adult.  Here many of our psychological processes are being organised ‘behind the scenes’ before being made available to consciousness. As Assagioli writes, they are “those things that are latent, quiescent: or active in our personality but we are not aware of at the moment.” (Assagioli, Miller, 1973) This is the region of the Pre-Conscious.
In the Middle Unconscious we find energies associated with our relationships, status and self-esteem. These energies are connected to our higher emotions and rational beliefs about life, such as our political, religious and social attitudes. Here we find the more or less conscious values we have adopted in life as a result of our education and socialisation. Here we store our conscious self-image and establish an identity, which then enable our self-expression and the development of boundaries. We discover here our need for friendship, belonging and for finding our place in a group and society. Through these we develop our creativity and talents supporting our life path. Here too we find inhibitions, fear and frustrations stemming from challenges and trauma of our teens, a time when we develop our self-conscious personality and become adults. These affect our sense of identity and self-worth, and consequently our relationship to love, work and status.
When the self is identified with this region and has its focus here, the Lower Unconscious is nevertheless active. But unless you have unresolved issues around safety and security, it recedes into background as a focus for identity. If there are such issues, when they are activated, we become fixated here until they are resolved. Our fixations cause “childish” behaviour because they represent unresolved needs from childhood requiring attention. The integration of these energies makes us more reflective and self-aware.
In the upper part of the Middle Unconscious we find more holistic mental energies. These trigger the urge to self-actualize. This is the culmination of the personality, the inspiration to create a truly successful and active life according to the existing values. Read more here: https://kennethsorensen.dk/en/the-psychosynthesis-model-of-the-personality/