we get the indistinct effect of both; but it must be observed that the lines must neither be too near together, nor too far apart, else the effect of the parallelism is either impaired or entirely destroyed. The whole surface of an object, as, for instance, of a vase, may be ornamented by a great number of parallel lines, and this is often the case in primitive or rude art; but, with culture, comes the tendency to draw more or less narrow bands of lines following the most important lines of the object.
A further step is taken in the attempt to make two parallel lines more agreeable to the eye by filling in the space between them with lines, drawn in various directions, and it is in this way that the frets have originated. By drawing equidistant parallel lines directly across between the two main lines, as in Fig. 3, we make a series. This, as
| Fig. 3. | Fig. 4. |
 | |
it exists in the drawing, is a series in space, but, as it grows up under the hand, or is examined by the eye, it is a series in time; and, in looking from A to B, an effect is produced upon the eye analogous to that produced upon the ear by the repetition of a musical note, with the same interval.[1] If lines be drawn only part way across, from each side alternately, as in Fig. 4, we have a sort of rhythm produced. If the lines all reach the centre, they may be, and often are, even in very savage art, connected together by twos, as in Fig. 5. This produces a series of units, each one of which is pleasant to examine with the
| Fig. 5. | Fig. 6. |
 | |
eye. This is the simplest form of the fret. If the lines are drawn not quite to the centre, they may be united by oblique lines, as in Fig. 6, A, and lines drawn past the centre may be connected in the same way, as in C, but neither of the resulting units is very agreeable to the eye, and such attempts are characteristic, either of a rude stage
- ↑ Irregularity in the interval interrupts the æsthetic effect. As each unit in the series falls on the yellow spot and is distinctly perceived, an effect is produced upon the brain which has a certain duration, gradually fading away. If the units are separated by the same intervals, these aesthetic effects will be alike; but, if they follow one another irregularly, the effect produced will be irregular, unexpected, and consequently disagreeable. The lengthening or diminution of the intervals, according to certain laws, heightens the æsthetic effect by relief from monotony; and this appears to be the least of the pleasure we derive from gradation in tint or shade.
