Man’s spirit

It is quite apparent to the seeing mind that a man’s spirit is something very different from his physical body. The spirit is changeless, indestructible. The progress and development of the soul, the joy and sorrow of the soul, are independent of the physical body.
If we are caused joy or pain by a friend, if a love prove true or false, it is the soul that is affected. If our dear ones are far from us—it is the soul that grieves, and the grief or trouble of the soul may react on the body.
Thus, when the spirit is fed with holy virtues, then is the body joyous; if the soul falls into sin, the body is in torment!
When we find truth, constancy, fidelity, and love, we are happy; but if we meet with lying, faithlessness, and deceit, we are miserable....

`Abdu'l-Bahá: Paris Talks