Ryōhen (良遍, 1194-1252), was a prominent Yogacara-Buddhist scholar and faithful disciple of Jōkei, often credited as a reformer of Japan’s Hossō sect during the medieval period in Japanese Buddhist history. In James L. Ford’s book on Jokei and Medieval Japanese Buddhism, Professor Ford quotes this famous “restorer” when he describes the famous Buddhist metaphor of waves and water succinctly (Japanese terms added by Prof. Ford):
Although there seem to be a multitude of waves, it is not a real multitude, for the waves are causally produced (enshō), phantom-like (nyogen) dharmas that defy the comprehension of the unenlightened mind. If the waves were unchanging, real (kenjitsu) objects they would be completely different from water. But since the waves are nonsubstantial (koke), they are in harmony (sōwa) with the water and are neither completely identical to, nor completely different from, it (fusoku furi). From this analogy, you can understand the relationship between phenomena and their underlying substance. (pg. 60)

The key to understanding this is that phenomena (things, thoughts, feelings, ideas, everything) exists like the waves. It’s existence is contingent on external factors (like the wind and water), and therefore temporary, not permanent. They are causally produced, in other words. Once those external factors are no longer in harmony, the phenomena in question will change or fade.
The ‘underlying’ substance here is not meant to imply ‘pantheism’ or ‘oneness’ (in the New Age sense), but rather the causes and conditions that cause something to arise. All waves, like all phenomena, have a commonality of having a contingent, temporary existence. Such phenomena are not entirely separate in existence, but aren’t “one” either. The truth lies somewhere in between.
This is what Buddhism defines as “emptiness” (e.g. of a permanent, separate nature) or in the classic Sanskrit term “sunyata” (pronounced ‘shoon-yata’). In the Heart Sutra text, one of the most fundamental to East Asian Buddhism, this is all summed up very succinctly:
色 不 異 空
shiki fu i ku
空 不 異 色
ku fu i shiki
色 即 是 空
shiki soku ze ku
空 即 是 色
ku soku ze shiki
Which means something like: Form is not different than emptiness; Emptiness is not different from Form. Indeed, form is emptiness; Emptiness is form.
So when you have angry thoughts, or see something you don’t like, just remember the water and wave analogy. You can’t be angry if you don’t have angry thoughts. 😉 For the good things in life, remember that they too are waves and will only stay around if conditions allow them to do so. Reflection on such things I hope will lead people to a more balanced view of the world and self.
Namu Amida Butsu
Namu Kanzeon Bosatsu