π

(do baú das frases gregas cuja versão alemã já aqui tinha sido explorada)

ἀεὶ ὁ θεὸς γεωμετρεῖ

"God always geometrizes", Plato.

Plutarch elaborated on this phrase in his essay: Πῶς Πλάτων ἔλεγε τὸν θεὸν ἀεί γεωμετρεῖν "What is Plato’s meaning when he says that god always applies geometry" [No Banquete 8.2.1 = 718c]. Based on the above phrase of Plato, a present day mnemonic for π (pi) was derived:

ἀεὶ ὁ θεὸς ὁ μέγας γεωμετρεῖ τὸ σύμπαν :: Always the great God applies geometry to everything. 

π = 3.1415926... 

ἀεὶ - 3 letters

ὁ - 1 letter

θεὸς - 4 letters 

ὁ - 1 letter

μέγας - 5 letters

γεωμετρεῖ - 9 letters 

τὸ - 2 letters

σύμπαν - 6 letters