Hahnemann believed that in homeopathy, you should only prescribe based on the primary effects of medicines. The primary effects of coffee are to increase your energy and mood. Would you ever say that coffee causes sleepiness and depression? No. Opium’s primary effects are to remove pain and make you sleepy (among others). Would you ever casually say that opium makes you more awake and makes you feel more pain? No. You might say that in the long run coffee makes you tired and opium increases pain, which is how we colloquially talk about secondary effects of medicines, but we wouldn’t say coffee primarily depresses you or makes you tired.