Tiruvalluvar

“ Who know not with the world in harmony to dwell,
May many things have learned, but nothing well.
Those who know not how to act agreeably to the world, though they have learnt many things, are still ignorant. ”

“ The envious soul in life no rich increase of blessing gains,
So man of 'due decorum' void no dignity obtains.
Just as the envious man will be without wealth, so will the man of destitute of propriety of conduct be without greatness. ”

“ Knowing that 'due decorum's' breach foulest disgrace will cause.
Those firm in mind will not slacken in their observance of the proprieties of life, knowing, as they do, the misery that flows from the transgression from them. ”