In works like What Is Ancient Philosophy and Philosophy as a Way of Life, French classicist Pierre Hadot argues that, in the ancient world, the word philosopher was used primarily to refer to people who transformed their way of living through spiritual practices—and not, as in the modern world, to someone devoted to the reading and writing of specifically philosophical texts. Along similar lines, in You Must Change Your Life, German philosopher Peter Sloterdijk argues that the concept of religion should be replaced by a concept of spiritual practice, or anthropotechnics, the regimens of spiritual training whereby human beings strive to shape themselves through repetitive actions. Importantly, both of these thinkers are attempting to revive spiritual practice not only as scholarly concept but also as a living exhortation, for human beings to once again take up the crucible of disciplined self-transformation.
That being said, the ancient understanding of spiritual practice remains radically different from the way spiritual practice manifests for a contemporary thinker like Sloterdijk. This difference, in turn, stems from a profound disagreement concerning the nature of reality itself. Generally speaking, ancient philosophers understood reality to be fundamentally harmonious, peaceful, and good—and within this vision, spiritual practice was understood in terms of reconnecting to this fundamental goodness. In modern thought, by contrast, reality is generally understood to be fundamentally violent, chaotic, and ultimately indifferent to human flourishing—and within this alternative view, spiritual practice is then understood in terms of the cultivation of self-control, as part of a larger cultural project to transform the indifferent natural world into a comfortable human home. As for ancient spiritual practice and its concomitant cosmology, these are criticized from the modern perspective as being nothing more than a flight into illusion, motivated by terror at the as-yet-uncontrolled world of nature.
If the modern critique of ancient spiritual practice begins with a critique of cosmology, the ancient critique of modern cosmology would begin from the opposite side of the spectrum, with a critique of modern spiritual practice. More precisely, the ancient practitioner would argue that modern cosmology is actually the result of a flawed approach to spiritual training. This critique turns on the location of what Hadot calls practical physics within the ancient curriculum of spiritual development. In short, the widespread historical narrative, whereby the infinite depths of space and time only became thinkable after Copernicus and Galileo, is actually not true; people have been contemplating the way human life appears from the perspective of the infinite abyss for thousands of years, and the moral upshot of this practical physics was the same in the ancient world as it is now: to inculcate a sense of humility, shared vulnerability, and universal human solidarity. In the ancient world, however, this perspective was not seen as the single, scientific truth of the human condition, but rather was understood as an imaginative spiritual exercise. Moreover, this exercise was itself set within a larger curriculum of training that began with the practice of selfless moral discipline. This is because the ego-dissolution that arises from this “view from infinity” can be spiritually dangerous, leading to a sense of fatalism or even nihilism—the idea that the only good is the power to ensure our own pleasure and survival within a fundamentally meaningless universe. According to the ancient philosophers, however, this conclusion, and the abyss of terror, as well as the sense of ontological despair often experienced by modern people, would be the logical results of an incorrect approach to spiritual training: namely, the precocious dissolution of the ego in the infinite, but without the preliminary cultivation of a relatively selfless ego that can peacefully endure its own dissolution. By the terms of this ancient curriculum, meanwhile, the proper pursuit of these two sides of spiritual life—moral selflessness and self-dissolution—would eventually give way to the experiences that Neoplatonists referred to with the word metaphysics, and which 3rd-century theologian Origen describes in terms of the experience of infinite love.
Mysticism, historical and contemporary