In homeopathy, homeopathic dilution (known by practitioners as "dynamisation" or "potentisation") is a process in which a substance is diluted with alcohol or distilled water and then vigorously shaken in a process called "succussion". Insoluble solids, such as quartz and oyster shell, are diluted by grinding them with lactose (trituration). The founder of homeopathy, Samuel Hahnemann (1755–1843) believed that the process of succussion activated the "vital energy" of the diluted substance, and that successive dilutions increased the "potency" of the preparation, although other strands of homeopathy disagree.