Euclid

There is no royal road to geometry.

The whole is greater than the part.

Things which are equal to the same thing are also equal to one another.

If equals be added to equals, the wholes are equal.

If equals be subtracted from equals, the remainders are equal.

Things which coincide with one another are equal to one another.

Let it be granted that a straight line may be drawn from any one point to any other point.

Let it be granted that a finite straight line may be produced to any length in a straight line.

Let it be granted that a circle may be described with any center and any radius.

Let it be granted that all right angles are equal to one another.

And that, if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, if produced indefinitely, meet on that side on which are the angles less than the two right angles.

A point is that which has no part.

A line is breadthless length.

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.

A plane angle is the inclination of two lines to one another in a plane which meet one another and do not lie in a straight line.

And when the lines containing the angle are straight, the angle is called rectilineal.