Let us take the first Principal of Art, STABILITY.
Stability is perhaps more applicable to the art of bonsai than any of the other art forms. Nevertheless, it is the very basis of the structural beauty of your Bonsai.
Unless your plants are balanced most styles will look as if something is not quite right, but what? Very often it can be as simple as tilting the root ball and trunk until the apex is on or past the vertical, 0.deg. But until one realises where the direction lies, the tilting can cause the plant to appear unstable.
After changing the trunk angle the attitude of the apical direction is most important. At all times a bonsai must impart a positive bearing. In most cases the apex will need to be lifted if it is angled 45deg. or greater. This applies to the upright styles including domed profiles, which will have the highest mass of foliage in the appropriate position. Failure to do so will, in most cases, impart a pitiful aspect instead of a growing, vigorous posture.
The root-system also plays an important role in establishing and maintaining stability, but more about the roots next month.
What about Stability in association with the root system?Imagine a tree firmly anchored into the ground, initially by the taproot, then by the primaries and the evenly spreading surface rootage.
Despite any change from upright to a more leaning angle, the tree remains firm, the profile of the root system is altered from the even rootage of an upright tree to what I like to describe as having acquired character. Roots under the lean have been forced to compress to fit into the newly reduced length caused by the altered angle. This results in what is known as buttressing. A lesser angle will have a mild buttress, whilst the greater the lean, the more massive the buttressing.
Conversely, the other side will have stretched to fit into the extended length. This shows the roots are still holding by growing deeply into the ground.
This realistic explanation is compatible with both Art and Horticulture, and is an adjunct to the Fine Art of Bonsai.