DURING THE SECOND HALF of the nineteenth century, empirical science had gradually become the predominant paradigm for assessing and determining knowledge about the human being. Yet such “materialistic” models of knowledge production seemed for many thinkers of the era to deplete human subjectivity and spirituality of its capacity for shaping human meaning and identity. Importantly, this empirical—purportedly “objective”—view of the human being emerged concurrently with debates about Darwin's Origin of Species (1859), whose theories of natural selection and evolution served as the critical harbinger for this dispute. As a result, many thinkers grappled with the apparent mutual exclusivity of scientific knowledge about the human being and human spirituality. Specifically, many intellectuals of the era, including such prominent scientists as Ernst Haeckel (1834–1919; zoologist and Darwinist) and Wilhelm Ostwald (1853–1932; chemist and Nobel Prize winner [1909]), wrestled with the purported contradiction between an empirical (material) understanding of human life and a spiritual one. In fact, they sought to resolve this perceived crisis of identity (triggered by the conflict between material and spiritual worldviews) by asserting a scientifically defendable model of human life that incorporated rather than excluded spirituality—a model that Todd Weir has termed a “fourth confession.”

In the case of Wilhelm Ostwald, for instance, Caspar Hakfoort identifies three aims of his spiritually grounded scientific philosophy: “striving towards a unified science of nature; its use as the basis for an all-embracing philosophy; and the effort to realize this philosophy in practice, as a secular religion to replace Christianity.” These traits are also generally applicable to many of the era's secular movements and their acolytes who attempted to reestablish commonalities between new science and spiritual identity. Moreover, open hostility to Christianity as a failed source for renewing human spirituality pervaded their publications and speeches, but tended to be denomination specific. Most of these innovative scientific- religious thinkers came from a Protestant heritage, including Haeckel and Ostwald. Unsurprisingly, these recurrent attacks were levied against the Catholic Church and what Ernst Haeckel deemed in his monist treatise and bestseller Die Welträtsel (World riddle, 1899; in English as The Riddle of the Universe, 1900), its “ultramontanen Geistesthyrannei” (ultra montane spiritual tyranny).