I love going back to some of the original books about gardens. One of the great ones, The Craft of Gardens by Ji Cheng, from about 1630, provides detailed tips on how to create a garden in the Chinese tradition, and includes a very detailed section on appropriate doorway shapes, material, sizes, and depth.
Cheng was trained as a painter and came to garden design in his middle age. He explains in his preface that he became known for designing gardens that incorporated mountains, lakes, and structures; that “collected together in [a] small space all the famous [natural] sights.” In his spare hours, he collected his observations and turned them into a book.
His audience was the emerging wealthy merchant class of the time. Alison Hardie’s translation of Ji Cheng’s work is an excellent addition to anyone’s garden book library. In her preface she summarizes Cheng’s approach, explaining that he, “emphasizes the importance of basing the garden design on existing nature and features… and uses poetic descriptions to build up an atmosphere which will inspire the would-be designer to create a garden that can express … emotions”.
The Craft of Gardens is organized around 4 themes: Situation, Layout, Buildings, and Scenic Features.
Within the 'Building' section, Cheng shares advice on doorways as an important element in any garden. They invite exploration and movement through the garden. As an opening in a wall, they provide a peek into what’s on the other side while reinforcing the shelter of a garden wall. Cheng wrote, “Not only can a doorway give a new look to a house, it can make a garden look more elegant too … thoughts can be aroused by a sudden vista, and inner feelings can be better expressed.” Given the distinct similarities between the doorway photos above, from The Surging Wave garden, and the ones in his book, one can only guess that the garden provided a source of inspiration. The doorways featured above include "Turned-in corners", the "Gourd", "Han dynasty vase 3", and the "Moon".