Task: Analyze the tweet's sentiment and assign it to either 'neutral or no emotion' or one or more of the specified emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust).
Tweet: Regret for the things we did can be tempered by time; it is regret for the things we did not do that is inconsolable. - Sydney J. Harris
This tweet contains emotions: 
pessimism, sadness