Spiritual naturalism, or naturalistic spirituality combines a naturalist philosophy with spirituality. Spiritual naturalism may have first been proposed by Joris-Karl Huysmans in 1895 in his book En Route.
Coming into prominence as a writer during the 1870s, Huysmans quickly established himself among a rising group of writers, the so-called Naturalist school, of whom Émile Zola was the acknowledged head...With Là-bas (1891), a novel which reflected the aesthetics of the spiritualist revival and the contemporary interest in the occult, Huysmans formulated for the first time an aesthetic theory which sought to synthesize the mundane and the transcendent: "spiritual Naturalism".
Long before the term spiritual naturalism was coined by Huysmans, there is evidence of the value system of spiritual naturalism in Stoicism: "Virtue consists in a will that is in agreement with Nature".
Spirituality (from the Latin root spiritus 'breath, spirit', from spirare 'breathe') is an overarching concept related to religion and "affecting the human spirit or soul as opposed to material or physical things". With many different definitions as scholars try to pin down exactly what it is they are defining, it has tended to have a more positive connotation than religion broadly in recent years because of its "association with personal experiences of the transcendent". It is seen as more positive because of trends toward privileging individuality, and so many different definitions are given it by many different people, any one of them unlikely to satisfy everyone.
In fact, the term is so broad and so dependent on who is using how, why, when, and in what context, that some have given up on trying to give it a comprehensive definition and just say that it means something different to all who use it. Perhaps a less necessarily contextual definition is found in the words of K. I. Pargament, who sees spirituality as a "search for the sacred" of each individual.