Fibonacci

A line is length without breadth.

The extremities of a line are points.

A straight line is a line which lies evenly with the points on itself.

A surface is that which has length and breadth only.

The extremities of a surface are lines.

A plane surface is a surface which lies evenly with the straight lines on itself.

To find the area of a triangle, multiply the base by half the height.

The diagonal of a square is incommensurable with its side.

The sum of the angles of a triangle is equal to two right angles.

In right-angled triangles, the square on the side subtending the right angle is equal to the squares on the sides containing the right angle.

I have written this book for those who wish to practice geometry.

Mathematics is the language of nature.

The patterns in numbers reveal the harmony of the world.