Anything you see anywhere, you want to appropriate and keep, not that they are necessary. So greed is a kind of urge of the mind towards appropriation of things which are not really necessary for the maintenance of one's life. If they are absolutely essential for the maintenance of your psycho-physical existence, they are permissible as necessary evils at least. But if they are not necessary for your existence and you can exist even without them and comfortably too from the point of your ultimate aim of life, then of course it would not be at all permissible to keep them. So greed is another expression of our finitude. This we have seen is to be kept in check by practice of charity.