Αν δεν μπορώ να φτιάξω ένα μηχανικό μοντέλο (ενός πράγματος) μέχρι το τέλος, δεν μπορώ να το καταλάβω.
As long as I cannot make a mechanical model (of a thing) all the way through, I cannot understand it. William Thomson Kelvin (Ουίλιαμ Τόμσον Κέλβιν) full quote: I never satisfy myself until I can make a mechanical model of a thing. If I can make a mechanical model, I can understand it. As long as I cannot make a mechanical model all the way through I cannot understand it.