Those who are enamored of practice without theory are like a pilot who goes into a ship without rudder or compass and never has any certainty where he is going. Practice should always be based upon a sound knowledge of theory.
—Leonardo da Vinci (1452-1519)
The trouble with people is not that they don’t know but that they know so much that ain’t so.
—Josh Billings (1818-1885)
Languages die ... mathematical ideas do not.
—G. H. Hardy (1877-1947)
Unfortunately, the gap between theory and practice is not as wide in theory as it is in practice.
—Anon.
These are my principles.
If you don’t like them, I have others.
—Groucho Marx (1890-1977)
There is no royal road to geometry.
—Euclid (c. 365-275 BCE), attrib.
——— ♦♦♦♦♦ ———
To all those who think an exercise like this one is worthwhile, and in particular to the memory of Lex de Haan, who is very much missed