There is no effort that we can make to still ourselves. True stillness comes naturally from moments of solitude where we allow our minds to settle. Just as water seeks its own level, the mind will gravitate toward the holy. Muddy water will become clear if allowed to stand undisturbed, and so too will the mind become clear if it is allowed to be still.
Like justness in a judge's decision, or beauty in a painting, soul is a quality of absoluteness in something relative. Understood profoundly, people are connected to the holiness of the world in such a way that they reveal a dimension of holiness in themselves, a dimension of depth that is absolute.