Milinda: “Then, ask as I may, I can discover no Nàgasena. Nàgasena is an empty sound. Who is it we see before us? It is a falsehood that your reverence has spoken.”

Here, Milinda is laughing at Nàgasena, and looking down at him!

Notice that, here Milinda is representing one of the extreme views — thinking something does not exist but indeed exist.

There are two extreme views:

The extreme of non-existence — thinking something does not exist but indeed exists The extreme of existence — thinking something exists but indeed does not exist

And Buddhism is said to be a middle way, that is not falling down into these two extremes. Also, in Tibetan Buddhism, there is a trained and reliable consciousness type — Valid Cognizer, that is able to measure what truly exists (thus avoiding at the two extremes above).