Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. The lectures which are reproduced, with some considerable additions, in the present book, were delivered in February of this year at Glasgow University, in accordance with the terms of the Alexander Robertson Trust. I take this opportunity of thanking Professors Reid, Cooper, Robertson and Stewart, of the Theological Faculty in the University, for the great kindness which I received at their hands.