This quote delves into the paradoxical nature of art, suggesting that an artist’s role is to create a convincing illusion of reality – a lie that feels true. In other words, the artist is crafting something that isn’t real, but it’s their job to make it seem so real, so true, that others believe it. This isn’t about deception in a negative sense, but about the power of art to create alternate realities, to evoke emotions, and to make us see things from new perspectives.

The "truthfulness of his lies" refers to the authenticity and emotional truth that can be found in art. Even though a painting, a novel, or a film might not depict real events or people, they can still portray real emotions, thoughts, and experiences. They can make us understand and feel things that we might not have otherwise. In this sense, the ‘lies’ of art can often tell us more truth about the human condition than factual accounts.

Applying this idea to today’s world, we can see how it’s relevant in many areas beyond just traditional arts. For instance, in the realm of virtual reality and video games, creators are constantly striving to make their artificial worlds feel as real and immersive as possible. They’re using technology to convince us of the "truthfulness" of their digital "lies."

In terms of personal development, this quote reminds us of the power of storytelling and perception. Just as an artist can convince others of the truthfulness of his lies, we can shape our own narratives and perspectives in a way that’s beneficial to us. This doesn’t mean lying to ourselves or others, but rather choosing to focus on and highlight certain aspects of our experiences and realities. For instance, by choosing to view challenges as opportunities for growth, we can change our perception and emotional response to them.