Light through an aperture keeps the source's shape
A ray takes the form of the luminous body, not of the hole it passes through
Two diagrams argue that a luminous ray passing through an aperture of any strange form ultimately prints a patch resembling the luminous source rather than the opening it crossed. The upper figure pairs a round luminous body with a screen pierced by a small cross-shaped hole, projecting toward a disc; the lower figure clusters several luminous circles behind a screen and shows the far-cast image returning to a round form. The second proposition insists a ray from a spherical light can never carry the angular quality of an angular aperture into its projection.
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The aperture's form is lost; the source's form survives
A luminous ray passing through an opening of any strange shape ultimately prints a percussion that resembles the luminous body it came from rather than the aperture it crossed. Although the paired screen bears a small cross-shaped hole, the projected patch tends back toward the round form of the source.
A spherical light cannot carry an aperture's angles
It is impossible for a ray born of a spherical luminous body to convey, over distance, the likeness of any angular quality belonging to the angular aperture through which it passes. However sharp the opening's corners, the far-cast image loses them and returns to the source's rounded shape.