As a group of countries with a shared heritage and common challenges, we can be so much more effective than a lone voice.
On the big issues that will impact our children's futures: Climate change, Plastic pollution, immigration, the impact of technology on jobs, the regulation of social media giants and the financial sector. There is not one of these really difficult issues that is not tackled better together.
At the world level conference table, as a group we can speak on equal terms with the USA, China and Russia, not to mention the fast growing economies of India, South America and Africa.
At the individual level, a young person's life is enormously enriched by experiencing other countries. Some degree of free movement is good for them, as it is for the host countries themselves.
If we go back to the reasons for which the European Economic Community was set up first with Iron and Steel, it was to prevent a re-run of the World Wars. War mongering insanity is never far away; so to join together to make it impossible is as valid now as it was in 1945 and indeed 1918.
Max Hastings has written perhaps the definitive article on how we should approach our European brothers and sisters. Everyone should read it.