There are similarities between Shakespeare's Sonnet 30 and Keats poem 'Ode To A Nightingale' particularly in the way both poets seem to sigh and feel sorrowful about things lost. Shakespeare uses the expression,' 'and with old woes new wail my dear time's waste'? ito express the emotion of regret. Keats also feels regretful, but his feelings are a little different. He feels sorry for the sickness and illness in the world, for melancholia, for man's dissatisfaction and depression - so much so that he considers what it would be like to follow the nightingale into the woods and never come back to this life.
Shakespeare's sonnet though, gets a little more heartening as it moves forward. He seems to find some comfort for the misuse of his hours on this earth, considering that after all they were well spen in the gaining of the riches of friendship, so his time wasn't really wasted. He seems to feel though that once he gets over past sorrows, new ones come along but that this is normal and natural and when he weighs everything up, the sad times and the happy times balance out. Keats' sorrow is more profound and one wonders if it is a permanent condition rather than a fleeting regret as the whole poem, although beautiful, is so melancholic.