Buddhist meditation is fundamentally concerned with two themes: transforming the mind and using it to explore itself and other phenomena. According to Theravada Buddhism the Buddha taught two types of meditation, samatha meditation (Sanskrit: śamatha) and vipassanā meditation (Sanskrit: vipaśyanā). In Chinese Buddhism, these exist (translated chih kuan), but Chán (Zen) meditation is more popular. According to Peter Harvey, whenever Buddhism has been healthy, not only monks, nuns, and married lamas, but also more committed lay people have practiced meditation. According to Routledge's Encyclopedia of Buddhism, in contrast, throughout most of Buddhist history before modern times, serious meditation by lay people has been unusual. The evidence of the early texts suggests that at the time of the Buddha, many male and female lay practitioners did practice meditation, some even to the point of proficiency in all eight jhānas (see the next section regarding these).[note 11]