Make things as simple as possible.
But not simpler.

Albert Einstein

Simplicity is the highest level of perfection.

Leonardo da Vinci

Do not complicate things.
Functional an reasonable solutions
are often the most attractive ones.

Jan Wilsgaard

The genius of a construction lies in its simplicity.
Anyone can build complicated.

Sergej P. Koroljow

Perfection is not achieved
when there is nothing left to add,
but when there is nothing left to leave out.

Antoine de Saint-Exupéry