The Duties of the Heart, by Rabbi Bachye, tr. by Edwin Collins, , at sacred-texts.com
The wisdom of the Torah * is divided into two parts:
I. The wisdom of the visible, that enables us to know the duties of the body and its members; and these include not only all the practical obligations
both of ethics and religion, but also all the physical obligations and restraints of a good and moral life.
II. The Duties of the Heart and Mind; duties that concern thought and feeling, and whose fulfilment is entirely in the hidden depths of the human heart and soul, and this is the wisdom of the invisible.
The duties of the heart and mind have all of them their roots in human reason, and, like some corporeal duties, would be recognised as binding even without revelation.