Head in the Clouds

Etymology:

• In 17th century, it was thought if you are not attentive about what is happening around, or you were daydreaming; it is like as if your head was in the air. Later the word “air” got changed into “clouds” as air moves all around from top to bottom, but clouds are subjected to always remain upwards. So when you are lost in thoughts, inattentive and are somewhere else than this expression is used suggesting that your ‘head is in the clouds’.