There is indeed a relationship between what stays in the stomach, what we cannot digest, what will not move appropriately from the stomach into the intestines, and that which saddens us. When we experience something genuinely tragic, it literally has a hardening effect on our digestive system. Even if it is almost unnoticed, it is nevertheless true that inner sadness causes us to work against our digestive processes. It is analogous to the food lying in your stomach like a stone. […]
Laughter is actually a process that makes us organically healthy. It acts as a healthy, undisturbed digestive system.
Source (German): Rudolf Steiner – GA 302 – Menschenerkenntnis und Unterrichtsgestaltung – Stuttgart, June 12, 1921 (page 21)
Translated bij Nesta Carsten-Krüger