The soul exists. That’s what it does. It doesn’t need traditional religion or occultist speculation to justify, let alone explain, its existence. The soul can simply be a thing-in-itself, free from purpose or the need to be redeemed or maintained or isolated for study. We often talk about the soul simply as the nonmaterial and thus mysterious aspect of our being, something we feel but can’t point to—or what is silent and constant, enclosed in our mortal coil. It’s also entirely possible that there’s no nonmaterial part of our being, and whatever intangible dimension of ourselves we feel or think we feel is just, as yet, unexplained by science. Or maybe we do have souls, but they die with the body. Given such speculative uncertainty, the closest approach to the soul for many without recourse to religious reassurance is “consciousness,” though this may amount to no more than replacing one word with another.
But if one wishes to give form to spirit, as well as cast off the yoke of moralism and dogma, the work of Gustav Theodor Fechner (1801–87), a nineteenth-century German physicist, philosopher, and psychologist, may be one place to begin. His work may have even more traction now, in a time of declining religious affiliation, when many people (the so-called nones) seek replacements for more dogmatic versions of spiritual reality but resist succumbing to mere hedonism or nihilism. A concept of the soul that neither defies naturalism nor depends on revelation or dogmatic authority is thus more appealing than ever.
Fechner’s Little Book of Life after Death (1836) is a modestly sized yet ambitious treatise on the immortality of the soul. (His later Zend-Avesta: On the Things of Heaven and the Hereafter  continues his thinking on the soul and related matters.) Available to the English-speaking world largely because of Mary C. Wadsworth’s 1904 translation (with a short introduction by William James, who praised its “daylight view” of the world “as inwardly alive and consciously animated”), the book presents the soul as something real and immortal, not just a philosophical construct. It treats the soul monistically, essentially dissolving the long-lived and very tired mind/body dichotomy. Fechner collapses dichotomies of God and human, material and spiritual, consciousness and matter, to create a unified tapestry of seeming immanent and transcendent reality.