Kotodama (言霊)
Kotodama was usually the spiritual power believed to be contained within words in Japan. It was also called Kotodama (言魂). The seion (a silent consonant) of kotodama was the law of fifty Japanese syllables of kototama forming Shinrabansho (everything in nature). The academic field devoted to studying kototama is called Kototamagaku.
Summary
It was believed that spoken words had some kind of influence on actual phenomena; that is, good things happened when good words were spoken, while ominous things happened when unlucky words were spoken. Because of this, all steps were taken to be sure that there would be no mistake in reading during the Shokushi (reciting a Shinto prayer) to the emperor. Even today there are taboo words that should never be used at weddings or other such occasions, and these words have their origins in the concept of kotodama. Japan was thought to have become a fortunate land through the power of kotodama, a so-called "land of happy kotodama." There were poems in "Manyoshu" (Collection of Ten Thousand Leaves) (written as 万葉集 or 萬葉集), 'Souls reside within words of the Yamato nation (Japan) of Shikishima (another name for Japan), and it will be filled with good luck due to the power they contain' ('志貴嶋 倭國者 事霊之 所佐國叙 真福在与具') by Kakinomoto no Hitomaro 3254 and '... and as told since the time of gods, the solemn souls reside in words of this country even in the eyes of the gods, and the nation will be filled with well-being from that power so the current population should use words while being wary of this fact...' ('... 虚見通 倭國者 皇神能 伊都久志吉國 言霊能 佐吉播布國等 加多利継 伊比都賀比計理..'.) by YAMANOUE no Okura 894.
This was from a general notion that 'koto' (言) and 'koto' (事) were the same from ancient times. Two different characters for koto, 言 (word, speech) and 事 (thing, matter) were used without distinction when kanji were first incorporated into Japanese, and Kotoshironushi (事代主, a god who appears in Japanese mythology) was also written as Kotoshironushi (言代主神) in the "Kojiki" (the Record of Ancient Matters).
The act of speaking out one's own will was called 'kotoage' (literally to speak out the word) and a bad result would be brought about if it was based on one's pride. For example, according to the "Kojiki" when Yamato Takeru climbed Mt. Ibuki he encountered an avatar of the god of the mountain, only to announce that since it was merely a messenger of the god, he would destroy it on his way back home. Since he had spoken out of pride, Takeru was cursed by the god and died. In another words, the ideology of kotodama was not the simple animistic ideology that god resided in everything, rather it represented the existence of the mind.
The kotodama of other cultural regions
There were ideologies seen in other cultural regions similar to kotodama. The Old Testament mentions holy spirits (called "???" in Hebrew), while in the New Testament such spirits are referred to as "Pneuma" in Greek. The word "pneuma" derives from the verb "pneo" (to blow), and refers to the breath of a powerful being. It is not known where the wind came from or where it goes.
A life is born when the wind blows.'
The reference to 'wind' here was 'Spiritus.'
In general, sound or words were believed to have the effect to chase away evil souls or spirits. This was performed in festivals, celebrations, or to get rid of evil spirits everywhere all around the world. Examples of the power of sound include the drums used during Shinto rituals and the flutes, bells, and drums used during carnivals.
Even the spiritual power of words were used as incantations or the command of the emperor. However, there are different interpretations of what the main 'koto' (事) (event) was. For example, some believed that "truth is a great rock upon which the church can be built," while others held that "if you seek the truth, gaze at your reflection in a mirror, and all shall be revealed," according to which truth was something that could be comprehended or grasped; yet both suggest that the "koto" (essence of the matter) itself is not something we human beings can ever know. This differed greatly depending upon culture, era, and individuals.