Hume: distinction between impressions and ideas

Impressions include immediate sense impressions of sound, sight, and touch. they are vivid mental sensations. Emotions are considered impressions for Hume. Ideas are secondary since they are merely about impressions and are memories, thoughts, or beliefs concerning our impressions. Any idea that cannot be found to reflect back on a simple impression is meaningless. Hume then dismisses the bulk of metaphysics as consisting of meaningless ideas.