“Analogy would lead us to conclude that the combinations of the primordial matter, forming our so-called elements, are as universal or as liable to take place everywhere as are the laws of gravitation and centrifugal force.”

The Futurist Reconstruction of the Universe http://www.italianfuturism.org/manifestos/futurist-reconstruction-of-the-universe/ Manifesto with Giacomo Balla, in: Direzione del Movimento Futurista, March 11, 1915. Translation by Caroline Tisdall, 1973.
Context: We Futurists, Balla and Depero, seek to realize this total fusion in order to reconstruct the universe by making it more joyful, in other words by an integral re-creation. 'We will give skeleton and flesh to the invisible, the impalpable, the imponderable and the imperceptible. We will find abstract equivalents for all the forms and elements of the universe, and then well will combine them according to the caprice of our inspiration, to shape plastic complexes which we will set in motion.

We have thus two definitions of mass; one by the law of inertia: mass is the ratio between force and acceleration. We may call the mass thus defined the inertial or passive mass, as it is a measure of the resistance offered by matter to a force acting on it. The second is defined by the law of gravitation, and might be called the gravitational or active mass, being a measure of the force exerted by one material body on another. The fact that these two constants or coefficients are the same is, in Newton's system, to be considered as a most remarkable accidental coincidence and was decidedly felt as such by Newton himself. He made experiments to determine the equality of the two masses by swinging a pendulum, of which the bob was hollow and could be filled up with different materials. The force acting on the pendulum is proportional to its active mass, its inertia is proportional to its passive mass, so that the period will depend on the ratio of the passive and the active mass. Consequently the fact that the period of all these different pendulums was the same, proves that this ratio is a constant, and can be made equal to unity by a suitable choice of units, i.e., the inertial and the gravitational mass are the same. These experiments have been repeated in the nineteenth century by Bessel, and in our own times by Eötvös and Zeeman, and the identity of the inertial and the gravitational mass is one of the best ascertained empirical facts in physics-perhaps the best. It follows that the so-called fictitious forces introduced by a motion of the body of reference, such as a rotation, are indistinguishable from real forces. ...In Einstein's general theory of relativity there is also no formal theoretical difference, as there was in Newton's system. ...the equality of inertial and gravitational mass is no longer an accidental coincidence, but a necessity.
"The Astronomical Aspect of the Theory of Relativity" (1933)

The Origins of Art (1966)
Other Quotes
Context: What I am searching for... is some formula that would combine individual initiative with universal values, and that combination would give us a truly organic form. Form, which we discover in nature by analysis, is obstinately mathematical in its manifestations—which is to say that creation in art requires thought and deliberation. But this is not to say that form can be reduced to a formula. In every work of art it must be re-created, but that too is true of every work of nature. Art differs from nature not in its organic form, but in its human origins: in the fact that it is not God or a machine that makes a work of art, but an individual with his instincts and intuitions, with his sensibility and his mind, searching relentlessly for the perfection that is neither in mind nor in nature, but in the unknown. I do not mean this in an other-worldly sense, only that the form of the flower is unknown to the seed.

Geometry as a Branch of Physics (1949)

Tomaszewski J. Kresy Wschodnie w polskiej myśli politycznej XIX i XX w.//Między Polską etniczną a historyczną. Polska myśl polityczna XIX i XX wieku.—T.6.—Warszawa, 1988.—S.101. Cited through: Oleksandr Derhachov (editor), "Ukrainian Statehood in the Twentieth Century: Historical and Political Analysis", 1996, Kiev

p, 125
Philosophy of Structures (1958)

Source: The Life of Pasteur (1902), p. 163
Context: I confess frankly, however, that I am not competent on the question of our philosophical schools. Of M. Comte I have only read a few absurd passages; of M. Littré I only know the beautiful pages you were inspired to write by his rare knowledge and some of his domestic virtues. My philosophy is of the heart and not of the mind, and I give myself up, for instance, to those feelings about eternity which come naturally at the bedside of a cherished child drawing its last breath. At those supreme moments, there is something in the depths of our souls which tells us that the world may be more than a mere combination of phenomena proper to a mechanical equilibrium brought out of the chaos of the elements simply through the gradual action of the forces of matter.

p, 125
"The Astronomical Aspect of the Theory of Relativity" (1933)

Address to the Society for Psychical Research (1897)
Context: Popular imagination presupposes spiritual beings to be utterly independent of gravitation, while retaining shapes and proportions which gravitation originally determined, and only gravitation seems likely to maintain.
When and if spiritual beings make themselves visible either to our bodily eyes or to our inward vision, their object would be thwarted were they not to appear in a recognizable form; so that their appearance would take the shape of the body and clothing to which we have been accustomed. Materiality, form, and space, I am constrained to believe, are temporary conditions of our present existence. It is difficult to conceive the idea of a spiritual being having a body like ours, conditioned by the exact gravitating force exerted by the earth, and with organs which presuppose the need for food and necessity for the removal of waste products. It is equally difficult, hemmed in and bound round as we are by materialistic ideas, to think of intelligence, thought, and will existing without form or matter and untrammeled by gravitation or space.