From the point of view of pure logic or philosophy, there will often be a dialectical tension between two concepts.
For example...
If I reflect on the concept of 'being,' I will be obliged to introduce the opposite concept, that of 'nothing.' You can't reflect on your existence without immediately realizing that you won't always exist. The tension between 'being' and 'nothing' becomes resolved in the concept of 'becoming.' Because if something is in the process of becoming, it both is and is not.

Auteur: Jostein Gaarder