This second series of lectures were delivered at the Royal Institution of Great Britain in February, March, April and May 1863. Most of the topics treated in them had for many years formed the subject of Muller's public courses as Oxford. In casting his notes into the shape of lectures to be addressed to a more advanced audience, he left out many things that were merely elementary, and made several additions in order to show the bearing of the science of language on some of the more important problems of philosophy and religion. Contents: language and reason; physiological alphabet; phonetic change; Grimm's law; on the principles of etymology; on the powers of roots; metaphor; mythology of the Greeks; Jupiter, the supreme aryan god; myths of the dawn; modern mythology.