"Hey Diddle Diddle" is a very short poem. It’s referred to as an English nursery rhyme. The origin of the write-up is not very clear. However, some records show that it’s linked with the rhyme that was first composed by James William Elliot who was a famous composer and nursery rhyme collector. The short poem was seen in his "National Nursery Rhymes and Nursery Sons" published in 1870.

The Structure
"Hey Diddle Diddle" is written in one stanza that contains 5 lines. It has a noticeable rhyme scheme. The writer was very plain in composing the lines.

The Meaning
"Hey Diddle Diddle" means different things to several scholars. The origin of the rhyme is not very clear. Hence, there have been several theories about it. One commentary says it is a corruption of the ancient Greek. Another commentary says it refers to several constellations. Other commentaries maintain that it depicts certain ladies and their relationship with some men.
In any case, the generally accepted meaning of the lines is that they refer to constellations. The "Diddle" means "to move with short rapid movement" or "to waste time in trifling". It also means "hoax" or "swindle’. The "Cat" refers to the constellation of Felis. "Fiddle"is the constellation of Lyra which refers to the ancient Greek stringed musical instrument. The "bull" or "cow that moved over the moon refers to the constellation of Taurus. The "dog" refers to the constellation of Canis Minor. The "dish" and "spoon" refer to the constellation of Ursa Major and Ursa Minor respectively.

In all, the 5-line poem still remains a subject of debate and inquiry among several scholars. Its true meaning is still very confusing.