Another anecdote relates how when ad-Du'alī's daughter came to him saying “Baba, ma ahsanu ‘s-samāi?” (what is most beautiful in the sky?) – he answered: “Its stars;” but she replied: “I don't mean what is the most beautiful object in it; I mean how wonderful its beauty.” - to this he remarked “You must then say, "ma ahsan ‘samāa (how beautiful is the sky).” And so he invented the art of grammar. Ad-Du'alī’s son, Abū Harb, relates that the first section of his father's composition (the art of grammar) was on the “verbs of admiration”.