Wave Theory

"...it is very difficult to isolate one wave, separating it from the wave immediately following it, which seems to push it and at times overtakes it and sweeps it away; just as it is difficult to separate that one wave from the wave that precedes it and seems to drag it towards the shore, unless it turns against its follower as if to arrest it. Then if you conside the breadth of the wave, parallel to the shore, it is hard to decide where the advancing front extends regularly and where it is separated and segmented into independent waves, distinguished by their speed, shape, force, direction. 

"In other words, you cannot observe a wave without bearing in mind the complex features that concur in shaping it and the other, equally complex ones that the wave itself originates. These aspects vary constantly ..."

—Italo Calvino, Mr. Palomar