Reflections on space and time
Euler lays out his views on the relation between metaphysics and mechanics. The truths of mechanics are "so indubitably constant" that they must be founded in the natures of bodies. Metaphysics is the study of the nature of bodies, therefore the laws of mechanics constrain metaphysical theories. In fact, any metaphysical idea or conclusion corresponding to a mechanical one must agree with mechanics in all of its implications. This applies in particular to space and time. Real, absolute, space and time are assumed by the laws of mechanics. Therefore, metaphysical arguments for the unreality of space and time must be unfounded and "hide some paralogism".
Original Source Citation
Mémoires de l'académie des sciences de Berlin, Volume 4, pp. 324-333.
Opera Omnia Citation
Series 3, Volume 2, pp.376-383.