"The definition of any given kind of thing is also the definition of a good thing of that kind: for a thing that is good in its kind is only a thing which posesses the attributes of that kind. To call things good and bad is to imply success or failure. When we call things good or bad not in themselves but relatively to us, as when we speak of a good harvest or a bad thunderstorm, the success or failure implied is our own. (...) a work of art is an activity of a certain kind; the agent is trying to do something definite, and in that attempt he may succeed or he may fail. It is, moreover, a conscious activity; the agent is not only trying to do something definite, he also knows what it is that he is trying to do; though knowing here does not necessarily imply being able to describe, since to describe is to generalize, and generalizing is the function of the intellect, and consciousness does not, as such, involve intellect. A work of art, therefore, may be either a good one or a bad one
(...) Any theory of art should be required to show, if it wishes to be taken seriously, how an artist, in pursuing his artistic labour, is able to tell whether he is pursuing it successfully or unsuccessfully: how, for example, it is posible for him to say, 'I am not satisfied with that line; let us try it this way...and this way...and this way...there! that will do.' (...) The watching of his own work with a vigilating and discriminating eye, which decides at every moment of the process whether it is being successful or not, is not a critical activity subsequent to, and reflective upon, the artistic work, it is an integral part of that work itself.
(...) What the artist is trying to do is to express a given emotion. To express it, and to express it well, are the same thing (...) A bad work of art is an activity in which the agent tries to express a given emotion, but fails."

- R.G. Collingwood (1889-1943)

Source: R.G. Collingwood. 1938. "Good Art and Bad Art", in The Principles of Art, pp. 280-5, Oxford: Oxford university Press. Printed in: Harrison & Wood (ed). Art in Theory. 1900-2000. An Anthology Of Changing Ideas. Malden: Blackwell Publishing. Also available from URL: http://books.google.co.uk/books?id=SWu4SB92fHMC&q=collingwood#v=snippet&q=collingwood&f=false