To demand a comprehensive, detailed, and fully documented account of the part of Berkeley's philosophy that pertains to the mind and its states is to demand the impossible. Unlike some prominent philosophers, Berkeley says too little, not too much. In his published writings he was completely silent on many central issues in the philosophy of mind. An example is animal minds. Neither the question do nonhuman animals have consciousness, nor the question are they capable of reasoning, is addressed in An Essay towards a New Theory of Vision, A Treatise concerning the Principles of Human Knowledge, or Three Dialogues between Hylas and Philonous, the three early books on which Berkeley's present-day reputation for philosophical acumen is founded. On the rare occasions when Berkeley did address topics in the philosophy of mind, all too often they received only cursory treatment. An example is causation. Berkeley vigorously challenged the practice of positing material causes. He affirmed volitional causation by minds, yet he never offered a systematic characterization of his alternative. He answered several objections to his denial of nonmental causes, but ignored numerous questions raised by his positive thesis. Berkeley's account of causation is thus programmatic and promissory, as is his philosophy of mind in general.