Task: Identify the primary emotion conveyed in the tweet and assign it to either 'neutral or no emotion' or one or more of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best capture the tweeter's mental state.
Tweet: It is no coincidence that Lacan recorded infants' jubilant reactions to their mirror images in the noise.
This tweet contains emotions: 
sadness