The physical senses and the soul’s powers have an equal and similar, not to say identical, mode of operation, especially when they are in a healthy state; for then the soul’s powers live and act through the senses, and the life-giving Spirit sustains them both. A man is truly ill when he succumbs to the generic malady of the passions and spends his whole time in the sickroom of inertia.
When there is no satanic battle between them, making them reject the rule of the intellect and of the Spirit, the senses clearly perceive sensory things, the soul’s powers intelligible things; for when they are united through the Spirit and constitute a single whole, they know directly and essentially the nature of divine and human things. They contemplate with clarity the logoi, or inward essences of these things, and distinctly perceive, so far as is possible, the single source of all things, the Holy Trinity.
~St Gregory of Sinai