Hippomancy
A method of divination practiced by the ancient Celts, who
kept certain white horses in consecrated groves. The horses
were made to walk immediately behind sacred carts and auguries
were drawn from their movements. The ancient Germans
kept similar steeds in their temples. If the horses crossed the
threshold with the left forefoot first on leaving the temples at
the outbreak of hostilities, it was regarded as an evil omen and
the war was abandoned.