.. _line:

line
====

.. index:: line

..

   A **line** is breadthless length.

   -- Euclid

A **line** is not a thing. It is a linear relationship established by two points. 

A line has one dimension. 

A line is straight. 

.. todo::
   must expand on the notion of **straight** as defined by a rule. 

This relationship is projected unto the plane. 

Nothing can be known about a line except for points that exist on it. 

.. todo::
   explain linear equation