Obelisks (Vatican City 1966)

First Day Cover Obelisks it reflects the thematic directions:

Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable sculptural processes originally used carving (the removal of material) and modelling (the addition of material, as clay), in stone, metal, ceramics, wood and other materials but, since Modernism, there has been almost complete freedom of materials and process. A wide variety of materials may be worked by removal such as carving, assembled by welding or modelling, or moulded or cast.

An obelisk  is a tall, slender, tapered monument with four sides and a pyramidal or pyramidion top. Originally constructed by Ancient Egyptians and called tekhenu, the Greeks used the Greek term obeliskos to describe them, and this word passed into Latin and ultimately English. Though William Thomas used the term correctly in his Historie of Italie of 1549, by the late sixteenth century (after reduced contact with Italy following the excommunication of Queen Elizabeth), Shakespeare failed to distinguish between pyramids and obelisks in his plays and sonnets. Ancient obelisks are monolithic and consist of a single stone; most modern obelisks are made of several stones.