Engels explained the universality of contradiction as follows

Engels explained the universality of contradiction as follows:

If simple mechanical change of place contains a contradiction, this is even more true of the higher forms of motion of matter, and especially of organic life and its development. ... life consists precisely and primarily in this--that a being is at each moment itself and yet something else. Life is therefore also a contradiction which is present in things and processes themselves, and which constantly originates and resolves itself; and as soon as the contradiction ceases, life, too, comes to an end, and death steps in. We likewise saw that also in the sphere of thought we could not escape contradictions, and that for example the contradiction between man's inherently unlimited capacity for knowledge and its actual presence only in men who are externally limited and possess limited cognition finds its solution in what is--at least practically, for us--an endless succession of generations, in infinite progress.

... one of the basic principles of higher mathematics is the contradiction that in certain circumstances straight lines and curves may be the same....

But even lower mathematics teems with contradictions. [7]

Lenin illustrated the universality of contradiction as follows:

In mathematics: + and - . Differential and integral.

In mechanics: action and reaction.

In physics: positive and negative electricity.

In chemistry: the combination and dissociation of atoms.

In social science: the class struggle. [8]

In war, offence and defence, advance and retreat, victory and defeat are all mutually contradictory phenomena. One cannot exist without the other. The two aspects are at once in conflict and in interdependence, and this constitutes the totality of a war, pushes its development forward and solves its problems.

Every difference in men's concepts should be regarded as reflecting an objective contradiction. Objective contradictions are reflected in subjective thinking, and this process constitutes the contradictory movement of concepts, pushes forward the development of thought, and ceaselessly solves problems in man's thinking.

Opposition and struggle between ideas of different kinds constantly occur within the Party; this is a reflection within the Party of contradictions between classes and between the new and the old in society. If there were no contradictions in the Party and no ideological struggles to resolve them, the Party's life would come to an end.

Thus it is already clear that contradiction exists universally and in all processes, whether in the simple or in the complex forms of motion, whether in objective phenomena or ideological phenomena. But does contradiction also exist at the initial stage of each process?

Is there a movement of opposites from beginning to end in the process of development of every single thing?