Bulls are a symbol of wealth, potency, beneficence, fertility, stability, virility, strength, reliability, provision, peacefulness, helpfulness and determination. For the Celts, the bull is the symbol of power and strength. They were also seen as a very virile creature, hence its association with fertility, and the power to procreate and extend the clans. Druids saw the bull as Solar energy and the cow as Earth energy. Celts also saw bulls as a symbol of luxury, wealth and supplies. This is due to the fact that for the Celts bulls were a source of income. For the Greeks, bulls are associated with Zeus as he transforms himself into a white bull. Tame and striking, Zeus joins a herd of cattle to capture the love of Europa as he was obsessed with her. Therefore, in this context the bull is a symbol of transformation and passion.