ts wrote:

>  There is a french expression for this 
>
>   La critique est aisee mais l'art est difficile
>
> Feel free to translate it in "anglois" if someone want to do it.
>

Those who can do,
those who cant teach (or critisise - much of a muchness)

At one school I attended I wasn't allowed to do technical drawing 
because I failed Latin!