View it as a particular opinion of how collections should be formed. Now take this particular opinion and enforce it by mechanical rules, so that valid collecti

View it as a particular opinion of how collections should be formed. Now take this particular opinion and enforce it by mechanical rules, so that valid collections are exactly those that can be formed by these rules. Voila, you got your type theory. If you want to be really bold, start infusing a notion of construction and proof into your collections. Good luck with finding a good and intuitive explanation for that process.