If you are trying to make things look more natural, curved lines are usually the way to go, but not necessarily so. A curved line may be grotesque and artificial to almost any degree, but it takes effort to make them look bad. Straight lines are specifically unnatural. Nature works only in curves. The planets move in curves, the smallest leaf is bounded by curves, and your own face doesn't even suggest a straight line.

You would be hard-pressed to find a natural straight line. Because the property a landscape gardener would work on is usually for a specific purpose, many unnatural features must be introduced. In many cases a curved line must be traded for a straight, for the sake of practicality.

This is sometimes true of walks and drives, which are usually the most conspicuous lines on the grounds. Even so, the general rule must be followed; drives and walks should be curved unless there is some good reason for them to be straight.

Of course, it is more complicated than just curved or straight. There are good curves and bad ones. If a curve is to be used, more thought and skill are required to save it from defect than if a straight line had been used instead. In the past, imitators of the English style laid out many unattractive curves.

The unmethodical, senseless, meandering, serpentine walks occasionally seen are not natural, nor are they at all artistic. Every curve in a drive or a walk should have an obvious purpose. Nothing exists in nature that does not have a purpose.

If a hill or a group of trees lies within the bend, there is a reasonable excuse for the curve. Objects that are not obviously of sufficient importance to demand a turn in the drive are palpably artificial and worse than useless. A flower bed in the curve of a drive is nothing but a waste. It might as well have just been put somewhere else, then the way would be shortened by straightening out the wiggle.

For any moderate distance, a double curve passing to one side and then to the other of a straight line, is usually useful. While it departs least from the straight line, it gives the most constant change of direction. It also presents a greater variety of views. It is essentially the "line of beauty, as long as this isn't overdone. Other combinations must suggest themselves to the designer who has any feeling for outline.

Grouped trees give an appearance of naturalness because, in nature, trees are almost always grouped. They are never in straight rows. A good, strong oak grows up; the patriarch of the forest.

Eventually, under the shelter of its spreading branches, a younger generation of oaks spring up, and so we have a group of oaks. A group of walnuts arises likewise in another place; and even the willows and poplars, which distribute seeds far and wide, are found growing grouped together where the environment is specially suited to their development.

Even though you don't normally find wall mounted fountains in nature, that's really no reason to deprive yourself of this lovely feature. There are enough to choose from, you will surely be able to find some that will accentuate and even blend in with your garden so well that others might think it grew out of the ground.