Given the emotion sadness and the tweet "What do I do with my heart that is trembling by just the thought of it?\nI really don’t know what love is", classify the intensity of the emotion displayed in the tweet. The classification options are: 0: no sadness can be inferred, 1: low amount of sadness can be inferred, 2: moderate amount of sadness can be inferred, 3: high amount of sadness can be inferred.