As Professors of Natural Philosophy we have one sad remark to make. The great majority of our critics have exhibited almost absolute ignorance as to the proper use of the term Force, which has had one, and only one, definite scientific sense since the publication of the Principia. As such men are usually among the exceptionally well educated, ignorance of this important question must be all but universal. In addition to what we have said on the subject in the text ([§ 97]), we would now only mention that the sole recorded case of true Persistency or Indestructibility of Force which we recollect having ever met with, occurs in connection with Baron Munchausen’s remarkable descent from the moon. It is, no doubt, a very striking case; but it is apparently unique, and it was not subjected to scientific scrutiny.

B. STEWART. P. G. TAIT.

April 1876.

TABLE OF CONTENTS.

Page
INTRODUCTION,[1]
CHAPTER I.
INTRODUCTORY SKETCH.
Article
Object of the Book,[1][22]
Two classes of speculators,[2][24]
Why doubters of immortality have lately increased,[3][26]
Belief of the Ancient Egyptians—
Separation between priests and people,[4][26]
The abode of the dead,[5][27]
Transmigration of souls,[6][28]
Embalming of the body,[7][28]
Belief of the Ancient Hebrews—
Position of Moses,[8-9][28]
His task,[10][29]
Belief of the Jews in an unseen world,[11][30]
Their belief in a future state,[12][31]
Their belief in a resurrection,[13][32]
Belief of the Ancient Greeks and Romans—
Unsubstantial nature of Elysium,[14][33]
Transmigration introduced,[15][34]
Rise of the Epicurean school,[16][36]
Uncertainty of philosophic opinion,[17][37]
Belief of the Eastern Aryans—
The Rig-Veda,[18][37]
It inculcates immortality,[19][39]
Double source of corruption,[20][40]
Zoroastrian reformation and tenets,[21-22][40]
Reformation of Buddha,[23][41]
Meaning of Nirvâna,[24][42]
Observations on ancient beliefs,[25-29][43]
Belief of the Disciples of Christ—
The resurrection of Christ,[30][47]
Future state taught by Christ,[31-32][49]
Perishable nature of that which is seen,[33][50]
The Christian Heaven and Hell,[34][51]
General opinion regarding the person of Christ,[35][52]
General opinion regarding the position of Christ,[36][53]
Spread of the Christian religion,[37][54]
Rise of Mohammed,[38][55]
Materialistic conceptions of the dark ages,[39][57]
Extreme scientific school,[40-41][59]
Points of similarity between this school and Christians,[42][60]
Varieties of opinions among Christians,[43-44][60]
Believers in a new revelation,[45][62]
Swedenborg and his doctrines,[46][63]
Remarks on Swedenborg,[47][65]
Modern spiritualists,[48-49][67]
CHAPTER II.
POSITION TAKEN BY THE AUTHORS—PHYSICAL AXIOMS.
Class of readers to whom the Authors appeal,[50-53][69]
Position assumed by the Authors—
Laws of the universe defined,[54][72]
Embodiment of some sort essential,[55][73]
Materialistic position described,[55][74]
Unjustifiable assumptions of materialists,[56-58][74]
Intimacy of connection between mind and matter,[59][77]
Essential requisites for continued existence—
An organ of memory,[60][78]
Possibility of action in the present,[61][78]
Principle of Continuity—
Illustrated by reference to astronomy,[62-75][79]
Breach of the principle illustrated,[76][87]
Extension to other faculties of man,[77][88]
Application of this principle to Christian miracles—
Erroneous position of old divines,[78][89]
Such opposed to the genius of Christianity,[79][90]
New method of explanation,[80-82][90]
Application of this principle to the doctrines of the extreme scientific school—
The visible universe will probably come to an end in transformable energy,[83-84][92]
It must have been developed out of the invisible,[85][94]
The Universe,—[86][95]
Similar errors committed by the extreme schools of theology and science,[87][96]
Application of this principle to Immortality—
Three conceivable suppositions,[88][96]
These reduced to two,[89][97]
Future course of our argument,[90][97]
The problem may be profitably discussed,[91][98]
CHAPTER III.
THE PRESENT PHYSICAL UNIVERSE.
Definition of the term ‘Physical Universe’,[92][99]
It contains something else besides matter or stuff,[93][100]
Grounds of our belief in an external universe,[94][101]
These in accordance with our definition of the laws of the universe ([Art. 54]),[95][102]
Meaning of conservation,[96][103]
[Use and Abuse of the Term Force,] [97][104]
Conservation of Momentum,[97][105]
Conservation of Moment of Momentum,[97][106]
Conservation of Vis Viva,[97][107]
Definition of Energy,[98-99][108]
Newton’s second interpretation of his Third Law,[99-100][108]
Friction changes work into heat,[101][110]
Historical sketch of the theory of energy,[102-103][112]
Transformability of energy constitutes its use,[104][115]
Case where energy is useless,[105][116]
Historical Sketch of Second Law of Thermodynamics—
*Carnot’s perfect heat-engine,[*106][117]
*Sir W. Thomson’s definition of absolute temperature,[*107][118]
*Melting point of ice lowered by pressure,[*108][120]
*Sir W. Thomson’s rectification of Carnot’s reasoning,[*109-*110][120]
*Professor J. Clerk-Maxwell’s demons,[*111-*113][122]
Degradation of energy,[114][126]
Future of the physical universe,[114-115][126]
Past of the physical universe,[116][128]
CHAPTER IV.
MATTER AND ETHER.
Inquiry regarding structure and material of the universe,[117][129]
Various hypotheses regarding matter—
(1.) Greek notion of the Atom,[118][130]
Speculations of Lucretius,[119-130][131]
(2.) Theory of Boscovich (centres of force),[131][137]
(3.) Theory of infinite divisibility,[132][138]
(4.) Vortex-atom theory,[133-134][139]
Remarks on these theories,[135-136][141]
Relative quantity of matter associated with energy,[137-138][142]
Universal gravitation—
Is a weak force,[139][144]
Two ways of accounting for it, [140][145]
Le Sage’s hypothesis,[141-142][146]
The Ethereal medium—
Its principal properties apparently incongruous,[143][148]
Analogy of Professor Stokes,[144][149]
Distortion and displacement of ether,[145][149]
Inferior limit of its density,[146][150]
Its supposed imperfect transparency,[147][151]
Remarks on ether,[148][153]
Remarks on the speculations of this chapter,[149-150][154]
Modification of the vortex-ring hypothesis,[151-152][155]
Possible disappearance of the visible universe,[153][157]
CHAPTER V.
DEVELOPMENT.
Nature of inquiry stated,[154][158]
Chemical development—
Changes in lists of elementary substances,[155][159]
Prout’s speculations,[156][160]
Experiments of M. Stas,[156][160]
Family groups,[157][161]
Mr. Lockyer’s speculations,[158-159][161]
Globe development—
Hypothesis of Kant and Laplace,[160][163]
Tendency to aggregation of mass,[161-162][164]
Process cannot have been going on for ever,[163][166]
Peculiarity of products developed inorganically,[164][167]
Life development—
Morphological and physiological species,[165][168]
Species regarded physiologically,[166][170]
Position of a certain class of theologians,[167][171]
Tendency to minor variations,[168][172]
Artificial selection,[169][174]
Natural selection, [170][175]
Unproved point in the Darwinian hypothesis,[171][175]
Remarks of Mr. Darwin,[172][177]
Development of the Darwinian hypothesis,[173][177]
Mr. Wallace’s views,[174][178]
Professor Huxley’s remarks,[175][178]
Position assumed by the authors,[176][179]
CHAPTER VI.
SPECULATIONS AS TO POSSIBILITY OF SUPERIOR INTELLIGENCES IN THE VISIBLE UNIVERSE.
Position of life in the present physical universe,[177][180]
Two kinds of equilibrium,[178][181]
Two kinds of machines or material systems,[179][182]
Two respects in which a living being resembles a machine,[180][183]
A living being resembles a delicately constructed machine,[181][185]
The delicacy is due to chemical instability,[182][186]
Delicacy of construction derived from the sun’s rays,[183][186]
Delicacy of construction in atmospheric changes,[184][187]
Worship of powers of nature—mediæval superstitions,[185][189]
Theory which attributes a soul to the universe,[186][190]
Real point at issue stated,[187][190]
Man presents the highest order of the present visible universe,[188][191]
The same idea pervades the Old Testament,[189][192]
And it likewise pervades the New Testament,[190-191][193]
CHAPTER VII.
THE UNSEEN UNIVERSE.
Decadence of the visible universe,[192-193][195]
Its arrangements apparently wasteful,[194][197]
Explanation of this,[195][197]
Memory of the universe,[196-197][198]
Connection between seen and unseen, [197-198][198]
Physical explanation of a future state,[199-201][199]
Dr. Thomas Young’s conception of the unseen,[202][200]
Objections to the proposed theory of a future state replied to—
Religious,[203][202]
Theological,[204-207][202]
Scientific,[208-212][206]
Quasi-scientific,[213][210]
Miracles and the Resurrection of Christ—
Objections of extreme school stated,[214][211]
How these are to be met,[215][212]
Development has produced the visible universe,[216][214]
Its atoms resemble manufactured articles,[217][215]
Development through intelligence,[218-219][215]
Idea presented in concrete form,[220][218]
Christian theory of the development of the universe,[221-227][223]
Life development—Biogenesis,[228-229][228]
Life comes from the Unseen Universe,[230][230]
Christian theory of life development,[231][232]
Position of life in the universe discussed,[232-238][233]
Meteoric hypothesis implies Discontinuity,[239][240]
Discussion of the notion that all matter is, in some simple sense, alive,[240-241][242]
Life, as well as matter, comes to us from the Unseen Universe,[242-243][243]
Position reviewed,[244][246]
Miracles possible without breach of Continuity,[245][247]
Peculiar communication with the unseen in the case of Christ,[246][248]
Apparent breaks are concealed avenues leading to the unseen,[247][249]
Probable nature of present connection between seen and unseen. Efficacy of Prayer,[248][250]
Angelic intelligences,[249][251]
Remarks on God’s providential government,[250-252][253]
Our argument may be very much detached from all conceptions of the Divine essence, [253][257]
Christian conceptions of Heaven,[254][258]
Two ideas in all Christian hymns,[255][259]
Possible glimpse into the conditions of the future life,[256-257][260]
Darker side of the future,[258][262]
Plato on the markings of the soul,[259][263]
Christian Gehenna,[260][264]
Mediæval idea of Hell,[261][265]
The process in the Gehenna of the New Testament apparently an enduring one,[262][267]
Personality of the Evil One asserted by Scripture,[263][269]
Brief statement of the results of this discussion,[264][270]
The scientific conclusion is directly against the opponents of Christianity,[265][271]
Criticism invited from leaders of scientific thought or of religious inquiry,[266][272]

INTRODUCTION.

The present age is one of very rapid progress in almost all branches of knowledge.

Like a wave swelling as it advances shoreward, this progress has violently transformed whole regions of thought, while it has repeatedly invaded others not heretofore deemed accessible to such catastrophes.

Presuming upon a soil of great natural richness, the inhabitants of these latter regions had for a long series of years given themselves up to a species of husbandry which was beginning at length to be detrimental in its effects.