"To begin with, there is a symbolic dimension to the pillar in the Japanese architecture. For example, tenchi kongen tsukuri (literally translated as the "palace construction of heaven en earth") was an early style that incorporated the idea of the symbolic pillar. Knowledge if this design has been passed down among carpenters since ancient time. It was probably a type of pit dwelling derived from the ancient housing that was constructed over a hole in the ground. In the early house design, two poles were erected at an appropriate distance from each other, then a ridgepole was placed across them and logs were leaned up against the ridgepole and interlocked a the top. This is the steep-rafter style known as gassho-zukuri (literary "praying hands" style) which looks more or less like a gabled roof place directly on the ground. Needless to say, the essential element of the structure was the pillar ; if a pillar broke or fell, then the whole structure (heaven abd earth) came crashing down instantly. The pillar was the linchpin of te house."
In The inner harmony of the Japanese house, Atsushi Ueda, Kodansha international, 1990, pp. 11-12.