In the desire to avoid needless obscurity I have sometimes passed over the views of well-known commentators in silence, and I hope this omission will not be attributed either to ignorance or to conceit. Wherever it was possible for me to trace a creditor I have acknowledged my debts, and in the appended list of References and Abbrevia tions' I have mentioned those commentaries which have helped me most. In common with all English students of Spinoza, I am greatly indebted to the works of Sir Frederick Pollock, the late Principal Caird, and the late Dr. Martineau; and my obligation does not end where my interpretation differs from theirs. But, so far as I am aware, no English book appeals only to readers who wish to make a special study of Spinoza's philosophy; and I venture to publish this attempt at a critical exposition of the Ethics in the hope that, whatever its shortcomings, it may help to fill a gap. I owe the interpretation of two of Spinoza's geometrical illustrations (below, p. 32 note 2 and p. 223 note 2) to the kind help of my colleague.