A physicist, mathematician & engineer were all asked for the definition of Pi. The Physicist answered, "Pi is approximately 3.14159265, to eight decimal places." The Mathematician turned up her nose and said, "Pi is the ratio of a circle's circumference to it's own diameter." The Engineer said, "Eh, it's about three.Not to kill the humor, but there's a very serious point worth underscoring in this.
Scientists have to qualify and speak with precision. Theorists always strive to speak in absolute terms. But the most practical and helpful of geniuses are the ones who know when it's okay to estimate, and that what's generally workable is far different - and far better - than anything that looks perfect on paper.
Of course, I do hope the joke is still funny. Not sad.
Science, Theory and Practical Working - there's a time for all three.