He used to live in that town, and he still knows all the streets by heart.
English Anabaptists often knew it by heart.
They might not write it down, but learned it by heart and had to repeat it just before baptism.
recite by heart.
Quinn didn't have to record current time settings; he knew that stuff by heart.
He also studied the first six books of Euclid and some algebra, besides reading a considerable quantity of Hebrew and learning the Odes of Horace by heart.