Street art - "the secret of happiness is..."

I stumbled on an interesting street art project (more about creator "Elay"and more images here).

• In the spirit of the season: happy holidays to everyone, and hopefully you have found the secret already or will find the secret soon.
• The image is an example of how leaving stuff out (of a PowerPoint presentation) can stimulate your audience to fill in the details themselves. Like (good) authors of novels, film directors, etc. try to do.