Is it worth thinking about the basics of mathematics without mathematics? What about mathematics and philosophy? Or physics about biology? The book “In the Essence of Things” answers this question in the affirmative. In the original form, the author combines mathematics with philosophy, cybernetics with physics, biology with linguistics, logic and semantics. Explains complex ideas in the natural sciences at a level that the lay reader can understand, using clear examples from a variety of areas of knowledge. The language of the book is accessible not only to a specialist, but also to any thinking reader who seeks to enrich his inner world with knowledge and reflection, to feel an additional impetus for the formation of non-standard and simple thinking. In the chapters: “Identity”, “Number”, “Life”, “Thinking” the reader finds himself “on the other side” of currently accepted logic. The book reveals themes of identification, relationships, part and whole, the liar paradox, learning by association, the mechanism of word formation and much more for a thinking person.