Since ancient times the circle is regarded as the most common and a universal sign and is found in all cultures. It is the symbol of the sun, its limitless or boundless aspect. It has no end or beginning, and no divisions, making it the perfect symbol of completeness and eternity.

The circle is a center point of focus and it makes the observer converge on a specific point within his perspective.
Circles were often drawn as protective boundaries, not to be crossed by enemy or evil and thus became a symbol of a boundary.

The TSA design for a circular door handle gives the door a clear indicator of a boundary, an enclosure and completion. It is the decisive boundary where the point of entering the house is demarcated and is a sign of the boundary between in and out.

The timeless circular handle, which can be pushed or pulled, brings totality, and wholeness. It focuses the eye of the approaching person on to a specific point before entering the house, thus creating a temporary abstract threshold of short duration prior to the moment of entry.

The handle floats before the external plane of the door and pulls the viewer into the house.