Depth and movement can be created depending on the thickness of the line. Our eyes continue to move up and down the flowing shapes. The lighter lines tend to come 'forward', while the darker lines tend to recede.
By varying the thickness and density of the line, you can convey a sense of real form and weight. Generally, lines are thicker and darker where there is shadow. Note the subtle change in thickness on the ribs, of the left of the body (ie the upper line)
Bending Figure, charcoal drawing
Diagonals create movement and/or vitality, as in this image of a fresh flower laden branch. Strength is gained through the simplicity of the composition, and the heaviness and repetition of the tapered lines.
Line can be both delicate and gutsy.
Like colour, there is so much you can do with line, and I've only just touched the tip of the iceberg here. As always, I love your comments and questions. So go on, drop me a line! :)
Stay tuned for the next post on Size.... (yes, it DOES matter)