 In the eighteenth-century context of moral theory, “sentiment” is a generic label for emotions. (Hume’s theory is sometimes identified as “sentimentalism,” but that term has unfortunate modern connotations—though see the entry on  moral sentimentalism.)  In Hume’s technical vocabulary, all emotions are impressions, not ideas. The sentiments associated with beauty and ugliness are reflective impressions. They are not “impressions of the senses.” Instead, they are responses to sensory impressions (T, 276).