"The quest for peace in all its forms is quite ancient, as old as mankind itself.
So, too, is the elevation of peace as a supreme value.
Nevertheless, there is still room to question the notion of peace of mind and its place in the hierarchy of human needs.
What, first of all, does it really mean?
One important definition is provided by the Jewish sages in the context of a lengthy discussion of the many virtues of peace:
"The Holy One, blessed be He, found no vessel but peace which could contain all blessing."
This beautiful passage, which makes peace the very basis of all good things, goes on to make a telling distinction–
Peace is a vessel that can contain blessing, but it can also contain nothing at all, can be an empty vessel.
Here is a truth with wide applicability, be it in the international or the interpersonal realm, or in the life of the individual soul.
Peace with no content, meaningless tranquillity, rest without sanctity—all are empty vessels.
At best, the emptiness is soon filled with positive content.
In all too many cases, however, the empty vessel becomes a repository for whatever comes along.
In the absence of anything else, rubbish and abomination can fill the void.
It is the same with empty peace of mind.
The tension and pressure seem to be gone, but nothing positive comes to take their place.
A vacuum results, an existence devoid of effort or thought, which is in no sense better than what preceded it.
A life of vain struggle can be relieved of pressure and anxiety and yet remain as vacuous and meaningless as before.
However, while stress is likely (particularly when unremitting) to be unpleasant, it has the potential of achieving meaningful, valuable change.
–Rabbi Adin Steinsaltz
From The Strife of the Spirit, p.6, by Rabbi Adin Steinsaltz