The phrase "were the air" can be replaced with a number of synonyms to convey a similar meaning, such as "filled the atmosphere," "permeated the surroundings," "impregnated the environment," or "saturated the space." These synonyms all indicate a pervasive and essential quality that surrounds us and is necessary for our existence. Whether it's the oxygen we breathe or the intangible quality of a person's presence, these expressions capture the importance of something that is all around us, but often goes unnoticed or taken for granted. The use of synonyms can help add variety to language and bring a fresh perspective to a particular idea or expression.