I know its the word transpersonal that's got you hung up, so to simplify matters I quickly add that its like spiritual psychology. But since I've got your attention, let's turn towards, not away from, the transpersonal...
The word is easy enough to break down: "Trans" is a Latin prefix meaning across, over or beyond, so attaching that to the word "personal", whose definition includes arising from personality and involving persons and human beings, we arrive at the concept of reaching beyond or transcending the individual or personal.
And I love the real definition of psychology. Its not the study of the mind, like most think, but the study of the soul. We all know "ology" refers to the study of, but did you know that "psyche" comes from the Greek word psuche meaning breath, life or soul:
"The breath of life, (the vital force which animates the body and shows itself in breathing life, in which there is a living being, a living soul) the soul (the seat of feelings, desires, affections, aversions [our heart, soul etc.]...The soul as an essence which differs from the body and is not dissolved by death (distinguished from other parts of the body)."
Yes, technically, psychology as we know it in our culture is the study of the mind and behaviors, but let's consider for a while this idea of the study of the soul, the essence of being. From that perspective, it makes considerable sense to study the soul through a lens which includes the transpersonal. Transpersonal experiences are characterized by non-ordinary states or shifts in consciousness that are beyond rational thinking. Doorways to the transpersonal include: near-death experiences, meditation, mystical experiences, ritual, trance, dreaming, the use of psychedelics & other medicines, yoga, dance, music, art, contemplation or even spontaneous gnosis. Such experiences are described as moments of awakening, ascention, samadhi, enlightenment, illumination, opening, liberation, or union.
It is interesting to me that native and Eastern cultures do not even have systems of psychology. For them, an understanding of the soul, and the evolution of consciousness or mind, is built right into their society. Instead of specialized psychologists and counselors to help people find their way out of themselves, they have monks, yogis, shamans, healers, priests, sages, and seers to guide the course. It is an invention of the modern mind to view the ego as the seat of the Self, as the highest authority, and one look into our rates of suicide, depression, anxiety, illness and neurosis will give you an idea of how that's been working out for us. Without a sense of something greater we are without meaning and feel lost.
Paradoxically that which gives us meaning is itself impossible to define. Yet, as my beloved colleague Russell Park PhD once said, you know you are close to truth when there is a paradox. Transpersonal psychology is the study of all paths to Truth, their methods, causes, effects, and the disciplines and practices they inspire. The human personality is not an end in its self, but a vehicle for the soul to navigate through the world. Through the application of spiritual techniques the highest levels of human potential may be realized and our pure essence of being remembered.
This is Transpersonal Psychology, and I find it fascinating.