Here's why:
* "Est" is the third-person singular present indicative form of "esse" (to be) in Latin. In English, we use "is" as the equivalent.
* In some English contexts, "est" might be used in a poetic or archaic style, but it's not standard usage.
Examples:
* Latin: "Deus est." (God is.)
* English: "He is." (using "is" instead of "est")
Let me know if you have any other grammar questions!