This being granted, science may be defined as a methodical processus of the connection and extension of our knowledge. It consists, in every department “in the exact relations established between observed facts, so as to deduce from the least possible number of fundamental data, the most extensive series of secondary phenomena, in renouncing absolutely the vain search after causes and essences.” So long as men seek to “explain” phenomena the theological and metaphysical spirit has not yet disappeared. Positive science abstains from all explanations of this kind. Thus, Newton has placed in the same category universal gravitation and the attraction of bodies. We cannot know what this mutual action of the stars and the attraction of terrestrial bodies are in themselves. But we know with full certainty, the existence and the law of these two orders of phenomena and moreover we know that they are identical. For the geometer weight is explained when he conceives it as a particular case of general gravitation. On the contrary it is weight which makes the physicist proper understand celestial gravitation. We can never go beyond such juxtapositions “of ideas.”[36] But while science brings together similar phenomena, its chief function is to _connect_ them, that is to say to determine them one by another according to the relations which exist between them. All science, says Comte, consists in the co-ordination of facts; and if the several observations remained isolated there would be no science. We may even say generally that science is destined, as far as the various phenomena permit, to dispense with direct observation, in allowing us to deduce the greatest possible number of results from the smallest number of acquired data. If a constant relation is found to subsist between two phenomena, it becomes useless to observe them both; for from the observation of one the variations of the other will be deduced. But the first may in its turn be the function of a third, and so on; until at last we conceive a constant connection between all the phenomena of a given order, which may allow us to deduce them all from a single law. Such for Comte would be the perfect form of science: how near it is to the Cartesian ideal! “The positive spirit,” he says, “without failing to recognize the preponderance of reality directly ascertained, tends to enlarge the rational at the expense of the experimental domain, by substituting the prevision of phenomena to their immediate observation.” Scientific progress consists in diminishing the number of distinct and independent laws, by continually multiplying their respective connections.[37]