‘A rolling stone gathers no moss’ is a proverb which literally means that a stone which keeps moving or keeps rolling does not have any moss accumulated on its surface.
Moss is a plant that grows in the damp and attaches itself with tiny thread to the objects that are close to where it grows the trees, the ground and the stones nearby. Growth implies time and the stone that does not remain immobile will not have the time for the moss to grow on it.
However, metaphorically it has two diametrically opposite interpretations.
Traditionally it is interpreted to portray a person of nomadic qualities, unwilling to settle down in a place, thereby avoiding collecting any material wealth and at the same time not having any responsibilities to shoulder. In this case it is seen as a virtue to adapt stability and accumulation. A person who keeps wandering never gets to builds up roots either culturally or socially and will not be able to accumulate any wealth. On the other hand he is seen as a person avoiding his responsibilities such as having a family which essentially needs stability. Seen in this light the person seems to be unworthy and gathering the ‘moss’ seems to be the more desirable element.
The first usage in English seems to be in 1546 by John Haywood in his book on Proverbs.
However, the contemporary interpretation has a more positive outlook. According to this the person is dynamic enough to keep the process of growth or movement going to avoid stagnation in life. Mobility is seen as a virtue in this case. In a physical sense, a person who moves a lot, such as by walking, will remain in good health and will gather no moss, that is, keep physical ailments at bay.
Another way to interpret this can be that a person who is striving towards higher goals and keeps himself updated in terms of the knowledge and technology will be always in a state of growth and will never experience the ennui of stagnation and vegetation. The ‘moss’ in this case is not a desirable thing.
‘A rolling stone gathers no moss’ is a useful proverb to remind us the necessity to keep ourselves striving towards better and better goals in life.