From the Introduction of Tom Leinster's 2014 book Basic Category Theory:

Category theory takes a bird's eye view of mathematics. From high in the sky, details become invisible, but we can spot patterns that were impossible to detect from ground level. How is the lowest common multiple of two numbers like the direct sum of two vector spaces? What do discrete topological spaces, free groups, and fields of fractions have in common? We will discover answers to these and many similar questions, seeing patterns in mathematics that you may never have seen before.

(cf. Peter Smith's Logic Matters blog, and Cakes, Custard, and Category Theory (2016-02-14), Category Theory Concepts (2016-04-25), ...) - ^z - 2016-07-20