The Lectures which this volume contains were not prepared for publication by Professor Sidgwick, and are therefore unhappily without the modifications and improvements which they might have received at his hands. Indeed he did not give any directions with reference to their publication, but left them, with other ethical papers, in my care, to be dealt with as might seem most advisable. With regard to the Lectures on the late Professor Green and on Mr. Herbert Spencer, they are an examination, expository and critical, of the views of Transcendental or Idealist, and Evolutional Ethics, as put forth by their most distinguished exponents. Before the publication in 1874 of The Methods of Ethics the great constructive achievement of which was unification of Intuitionism and Benthamite Utilitarianism - the prominent doctrines in English ethical thought were the intuitional and utilitarian views, and these were currently regarded as being in thorough-going antagonism to each other. Later, Professor Sidgwick came to regard the Transcendentalist and Evolutionist schools as the principal rivals in contemporary English Ethics of his own system.