The rhomboid defined; parallel lines
The oblique parallelogram from the rectangle, and equidistant lines
Folio 2v defines the rhomboid, the oblique parallelogram that stands to the long tetragon as the rhombus stands to the square: its opposite sides and opposite angles are equal, but no angle is contained by equal sides. A slanted rhomboid is drawn above the text. Below, two horizontal lines illustrate the definition of parallel, or equidistant, lines, which continued straight will never meet.
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Definition of the rhomboid
The rhomboid arises from the rhombus as the rhombus arises from the square - but it comes from the long tetragon. It has equal opposite sides and opposite angles, yet no angle is contained by sides that are equal.
Definition of parallel lines
Parallel, or equidistant, lines are those which, continued in a straight direction, will never join together anywhere. Two horizontal lines drawn across the page illustrate the case.