This proverb literally means – Someone who does not settle in one place rarely prospers. This proverb refers to what is well-known about mosses and lichens – that they are slow-growing organisms that don’t thrive on disturbance. A sure way to prevent a colony of moss from growing on a stone is to move it about. As with all proverbs, it isn’t the literal meaning that conveys the meaning but the metaphor. A rolling stone refers to a wanderer, unable to settle to any job or lifestyle and is therefore characterised as unreliable and unproductive. (Deliberately sourced from a site with a .uk Domain (http://www.phrases.org.uk/meanings/a-rolling-stone-gathers-no-moss.html))
Now I reside in India, which is a country with a distinct monsoon season and as such the connotations associated with ‘Moss’ are all negative, something that needs to be cleaned and is deemed to be dirty and filthy. Taking this view the implication of the said proverb is entirely reversed, i.e. you must always keep moving so that no moss gathers on you, or in other words, you do not stagnate. In several poor translations of original English text that I have seen, the translators often resort to literal translations of idiomatic explanations that rarely transfer well between languages. The worst I have seen render these unintelligible, but there might be cases like this where the meaning is entirely reversed!