Even to positive science, we must be careful not to attribute an absolute character--that is to say, in a sense slightly different from the preceding one, but very frequently with Comte--a definite and immutable character. The laws which we can determine are never true except under certain conditions. We have no right to consider them as true _absolutely_. Newton’s law is demonstrated for our solar system: but do we know that it is verified in all the systems throughout space? Do not let us confound the world, which we can study with the united resources of observation and calculation with the universe, of which we know scarcely anything, and which outranges all our powers. In spite of the famous principle of the sufficient reason the absence of motives for negation does not constitute the right of affirmation, without any direct proof. Absolute notions, says Comte, seem to me so impossible that I would not even dare, whatever probability I may see in it, to warrant the necessary and unalterable perpetuity of the theory of gravitation restricted to the interior of our world, if one day, (which is moreover very difficult to admit) the precision of our present observations came to be perfected as much as we have done in comparison to Hipparchus.[40] In the same way, must not attraction have seemed to be an absolute quality (that is to say an immutable one) of bodies, since neither change of shape, nor the passage from one physical constitution to another, nor any chemical metamorphosis, nor even the difference between the state of life and death could modify this quality, so long as the integrity of the substance was maintained? The Newtonian conception came and destroyed entirely at a signal stroke this character which must have appeared so indestructible, by showing that the weight of a body is a phenomenon purely relative to the position of this body in the world, or, more precisely, to its distance from the centre of the earth.[41] In order that our positive science of any part of nature should be absolute, that is to say, final, it would have to be complete. But, as all things are caused or causing, helped or helping, according to Pascal’s expression, all the phenomena in a reciprocal universal action, all the laws relative one to another, our science will never be complete on any point. It only furnishes more or less imperfect approximations.[42] The discovery of new facts and new laws is always possible.