Swami Vivekanand Ji on idol worship

Here is an incident I found out while I was going through Swami Vivekanand Ji's bharat yatra.

During his "Bharat bhraman" Swami Ji reached Alwar, where he became acquainted with Maharaja Mangal Singh and on his request visited his palace. Initially the Prince had no faith in the Swami.
Here is a piece of conversation (debate) they had one night.

Swamiji, I have no faith in idol worship, said the Maharaja.

Swamiji replied, "An idol is only a symbol. It is not something to sneer at. Every devotee has his own way of realizing God. It depends on the individual's devotion."

*The Prince was not satisfied with Swamiji's explanation. There was a portrait of the Maharaja on the wall.*

The Swamiji asked the Diwan (chief minister) by his side, 'Whose picture is that?"

"The Maharaja's," replied the Diwan.

Vivekananda said, "Spit on it."

*The Diwan was taken aback. *

"Why are you unhappy?" asked the Swamiji.

* The Diwan thought this man was certainly mad.*

Swamiji explained: "After all, the photograph is just a shadow of your Maharaja. It is devoid of flesh and blood."

"But then it reminds us of the Maharaja, does it not?" said the Diwan.

The Maharaja then apologised to the Swamiji.