The number two and the intriguing dualism of nature. scientific curiosity and everyday concepts

The concept of duality together with the meanings, origins, and uses of number two, are thoroughly discussed, in an attempt to show how everyday concepts have much broader implications, and can be the source of an unlimited curiosity. After an introduction about the general characteristics and history of the number two and related 'twoness', some dualistic systems, which originated with the dawn of the civilization all over the world, are examined. The relevance of number two is examined in some scientific and non-scientific fields. Starting with the specificity of the number two in mathematics, the discussion examines the specific importance of some binary realities in physics, chemistry, and biology, including a paragraph on the symmetry-asymmetry 'twoness', and ends up with a discussion on less scientific dualisms. The binary theme becomes, thus, the guiding theme of a reality, which seems to justify the suspect that the universe is in fact a biverse.