We print in full the masterly reply of Prof. Tyndall to the attacks of his critics, which is prefixed as a preface to a new edition of the Belfast discourse. It was not to be expected that he would remain passive under the unscrupulous assaults to which he has been subjected; nor that, when he did speak, he would make any half-way work with his assailants. Our readers will agree that they have got no more than they deserve; and we think that every competent reasoner must admit that Prof. Tyndall's rejoinder to the main charges against his address is conclusive.
In regard to the wisdom of opening and pursuing this important question, there can, we think, be no serious doubt. It can be condemned only by condemning the general desirableness of discussion, the analysis of opinions, and the comparison of conflicting views. It has been wisely said that of the three states of mind, or stages of conviction—the unanimity of the ignorant, the disagreement of the inquiring, and the unanimity of the wise—the second is at all events the parent of the third. He who drags people out of the slothfulness and stagnation of ignorant unanimity, even though thinking engenders discord and dispute, is doing a wholesome and necessary work. This is what Prof. Tyndall has very successfully accomplished. If to concentrate public attention upon a subject of great and acknowledged importance, to summon the most powerful minds to its re-examination, and to secure the keenest scrutiny into all its aspects and bearings, be the way to arrive at its clearer understanding, then has the author of the Belfast address done an eminent service to his generation. Such services are always useful, but they become of high and especial value when the problems brought forward are new, or are old problems which have acquired new meanings by a change of the circumstances in which they are considered. The critics of Prof. Tyndall tell us that he has raised a very old question, one which comes up alike in every age, which is no nearer a settlement now than it was thousands of years ago, and which is just as insoluble for modern science as for ancient theology. But it is not easy to understand how the mere calling up of an obsolete and hopeless question, that derives no new significance from the present state of knowledge, should have made so profound an impression upon the strongest minds, in widely-separated countries, and in this age of absorbing intellectual activity. A startling statement may arrest momentary attention, but, if empty and futile, why should its interest be so sustained? For three months after the delivery of Tyndall's address we were deluged with comments, dissections, exposures, and refutations by the daily and weekly press, and, had it been as vacant of vital meaning and pertinent application as many allege, its force would long before this have been spent, and the subject would have died away as a mere superficial and transient excitement. But things have gone quite differently. The interest has increased rather than declined, and to the rattle of newspaper musketry begins now to succeed the roar of the monthly and quarterly artillery. And this for the adequate reason that new elements are at work, old questions are reshaped, and appear in new relations, while the controversy takes on an aspect that it never presented before, and requires to be searched and sifted