The 33-year old Dutchman enjoyed a bright spell at Parkhead a few years back before moving to Hull City and then onto Austrian outfit Rapid Vienna.
It was there, when dealing with constant injuries, that he realised he missed being a Celtic player.
"There aren't many better places to play football than Celtic Park, but it's only now I realise that,” he told SunSport.
"Maybe when you're there every day you don't completely appreciate what you have.
"In Scotland people are very serious about football. Everybody has an opinion or knows something about football. They talk about it all the time. It's a way of life.
"For instance, in Scotland you pick up newspapers and the back page is all football. Turn the page and it's football. And it's like that for page after page after page. Every club gets a lot of coverage.
“The Austrian outlook to football was totally different to what I knew. For that reason, I didn't enjoy it there.
"I admit, I couldn't adapt to that. It was a big change and I missed the British culture.
"In Scotland and England, football is the number one thing in the lives of some people. Everything revolves around it and I really like that mentality.”