Musician, poet, architect, novelist, in that order, Thomas Hardy must surely rank as one of this country's greatest men. But why? His novels are wonderfully crafted social observations, historical records and moral commentaries but then, so are many others. His poems - a vast body of sometimes variable work - are immediate and memorable, original and musical. But others are equally good. His architecture? I can't comment on his skill as an architect though I can be pretty certain that he must have been a more than useful musician, given what regular duties he and other members of the Hardy family undertook.
More than anything, perhaps, is Hardy's immense influence on other writers: and what he most consistently speaks to fellow authors is the importance of honesty. Hardy is always honest, uncomfortably so at times, and his style and idiom are as honest as his themes and his subjects.
That, probably more than anything else, is the true mark of greatness. It sounds easy doesn't it? But making great art out of honesty... that's another story!