What you want — to live without being constantly disturbed — is a great thing. Actually, it's the greatest thing of all. It almost raises you to the level of a god. The Greeks call this calm steadiness of mind euthymia. Democritus wrote an excellent treatise about it. I call it peace of mind. There's no need to translate so exactly that we copy Greek word forms. The important thing is to mark what we're discussing with a name that has the same meaning as the Greek term, even if it takes a different form. So what we're looking for is this: How can the mind always follow a steady, untroubled course? How can it be pleased with itself and look with pleasure at what surrounds it? How can it experience no interruption of this joy, but stay in a peaceful state without ever being lifted too high or cast too low? This is what I mean by 'peace of mind.'
What you desire, to be undisturbed, is a great thing, nay, the greatest thing of all, and one which raises a man almost to the level of a god. The Greeks call this calm steadiness of mind _euthymia_, and Democritus's treatise upon it is excellently written: I call it peace of mind: for there is no necessity for translating so exactly as to copy the words of the Greek idiom: the essential point is to mark the matter under discussion by a name which ought to have the same meaning as its Greek name, though perhaps not the same form. What we are seeking, then, is how the mind may always pursue a steady, unruffled course, may be pleased with itself, and look with pleasure upon its surroundings, and experience no interruption of this joy, but abide in a peaceful condition without being ever either elated or depressed: this will be "peace of mind."