The concept of Grammatical States is the cornerstone of نحو. Without the proper understanding of grammatical states you can end up saying The rat ate the cat when you actually want to say The cat ate the rat. An oft cited example for this is from the Quran: …و اذابتلٰی ﺍﹺﺑﺮٰﻫﻴﻢﹶﺭﺑﹽﹹﻪﹸ ُ…. "And remember when the Lord of Ibrahim tested him…"