The Quotations themselves have been divided into separate classes. The greatest number illustrate particular expressions, sentences, and paragraphs. These are arranged as foot-notes on the several pages of Text, and are referred to by the _small_ letters of the alphabet. Others, explaining or confirming principles, of general importance to the argument, have been distinguished by _capital_ letters, and placed at the end of the chapters to which they appertain. With this latter division are classed a third set of extracts, which aim at expounding certain special thoughts, and opening out to the real student useful paths of prolonged investigation. One circumstance connected with the Additional Notes, is alluded to at the bottom of page 27. Originally, I had made only a few citations from thoroughly sceptical writers. But, against this plan were urged the following objections. (1.) In arguing questions of all kinds, definite points are present to the mind of every disputant, and against them he directs his argument. His expressions are always antithetic to these points, and should they be left in the shadow, all antithesis is lost, and the real force of the argument obscured. Sometimes it is even mistaken;--a truth which may be illustrated by comparing the positions of great leaders in politics or theology with the positions occupied by their disciples. The former always speak by way of antithesis,--the latter seldom construe their leaders' words antithetically. Hence, the disciples never fail to outrun their teachers. Antithesis is in truth a verbal counterpoise; and where it disappears, balance is not seldom overthrown. Thus, said my advisers, your reasoning must necessarily suffer by a general loss of clear definition. Again, (2) they continued;--Since the time when you began your Essay, Scepticism in general, Materialism and Mechanism in particular, or, to speak briefly, the various denials of Theism, have ceased to be subjects on which reticence is feasible. An Address of Mr. Gladstone's delivered in a room, and spoken to a company of youths, soon became world-wide; it has been, and will be read, quoted, and commented on, wheresoever the English language is understood. One daily newspaper attractively written, devotes many of its clever pages to making known in a forensic manner the many different phases of sceptical opinion. And some religious journals explain, with complete freedom, what the disbeliefs are which they consider most reprehensible. Reticence, therefore, is simply thrown away. Some may desire to see it practised towards young people, but such "economizers" are, in effect, theoretical. They forget that the Battle of Thought comes to educated young minds along with the Battle of Life; and woe to the unprepared either way! They become, one and all, bewildered.