73. Let us now turn to another branch of the same subject. When Galileo first applied his telescope to the sun, he discovered the existence of sun-spots. Their solar origin was however for some time disputed, the schoolmen of that day, holding resolutely to the dicta of Aristotle, being indisposed to believe that there could possibly be any imperfection in the sun. The telescope alone was in fault. There was even a sermon preached on Galileo, the text of which was ‘Viri Galilæi, quid statis in coelum spectantes?’
However, as time went on, observation showed that spots were unmistakably solar phenomena, and these very imperfections are made use of by modern science to obtain for us information regarding the chemical and physical structure of our luminary. It also appears that the position and size of these spots depend upon the positions of the planets Mercury and Venus, and this as well as other phenomena indicate the existence of some mysterious bond between the sun and the various members of his system, possibly other than the law of gravitation, as we now understand it, can express.[31] In fine, simplicity of relation threatens to disappear, just as simplicity of motion disappeared before it.
74. Nevertheless in this triumphal march the progress has always been from the less to the more perfect, from the glimmering of early dawn to the clear morning light, if not to the bright beams of the noon-day sun. Temporary obstacles have appeared only to be surmounted, and like Augustine’s ladder to constitute a platform from which a higher and more comprehensive view might be obtained. Difficulties too, other than physical,—struggles, weariness, opposition—have been encountered and overcome, nor has there been anything like a grave defeat, or the production of permanent confusion. The concluding words of the Te Deum have been abundantly fulfilled in the experience of the astronomer. He has trusted in God, and he has never been confounded.
75. Here then we have an instance of what is meant by Continuity. It does not imply an easy progress, or a smooth level road; it is consistent with a temporary halt, perhaps not even inconsistent with a temporary break-down, or with momentary despair. We are met by difficulties of many kinds—the rock, the tangled growth, the swamp, the thick darkness, but never by the abyss. Nothing has occurred to convince us that our path has been absolutely wrong from the very commencement, and that we must altogether retrace our steps; and the same thing holds in other problems besides those of astronomy. Once we have accumulated sufficient trustworthy evidence to show us that we are in the right way, we are never afterwards irretrievably defeated.
Before proceeding further, let us here notice a peculiarity which, if it be clearly exhibited in the progress of astronomy, is yet by no means confined to that science, but appears to be characteristic of all physical knowledge.
Things are so arranged and the intellect of man is so constituted that we are led in the progress of science to recognise certain laws which appear at first sight to hold exactly, or which, in other words, have the appearance of absolute truths. As time passes on, and our instruments become more delicate, while our observations with them are multiplied, signs begin to show themselves of very slight deviations from exactitude in these laws.
Meanwhile, these approximate expressions of truth during the long ages (it may be) through which they have been believed, have taken such a hold upon the minds of men that all signs of their imperfect exactitude are at first utterly discredited. Ultimately, however, it is by means of these slight discrepancies that we are led forward to higher generalisations. This was well pointed out by Sir J. Herschel in his Discourse on the Study of Natural Philosophy. In fine, does not something analogous to the principle of continuity prevent us from supposing that we can ever arrive at the ultimate expression of truth on any, however limited, subject? Whenever, therefore, the language in which any scientific truth is embodied appears to us to savour too much of the absolute, is it not a proper and hopeful task to endeavour to break this down? It is on this account that we welcome all attempts to modify the expression of the law of gravitation, which, as our knowledge of it stands at present, seems to present too much of the appearance of an absolute and final truth.[32]
76. Our readers will now perhaps wish to have an example of what we should term a breach of Continuity,—this is easily given. Let us suppose for instance that the sun, moon, and stars were to move about in strange and fantastic orbits during one day, after which they returned to their previous courses. Here we should have an excellent example of a breach of Continuity, for even if things were so arranged as to prevent physical disaster, it is evident that the whole intelligent universe would be plunged into irretrievable mental confusion. Never again could it be said that astronomy is competent to explain the varied motions of the heavenly bodies. The observers would lay down their instruments, and the mathematicians their calculations, and the science would come to an end.
Other examples of a breach of Continuity may be as easily imagined. Suppose for instance that the gold of the world were to disappear for six hours and then return to it again,—should we not have all the social relations of men as well as their conceptions of matter thrown into irretrievable confusion? This would not, however, be due to the mere fact that something had disappeared from the visible universe. Individual consciousness we have seen is seemingly in the habit of doing so and again reappearing, and we do not trouble ourselves much about it.
Continuity, in fine, does not preclude the occurrence of strange, abrupt, unforeseen events in the history of the universe, but only of such events as must finally and for ever put to confusion the intelligent beings who regard them.