Sorting, matching, ordering, language, logic, spatial relations, recognition, organisation, planning, balance -- playing with blocks makes a deep and lasting impression.
Give a child a set of blocks. Watch motor skills develop. See them grasp physics and engineering principles as they find out how to stack and balance. Marvel as they make and break patterns and shapes.
And don't be too amazed when your children give their Uncle Goose blocks to their children. These are quality, classic, heirloom toys. They'll be handed down from generation to generation. They're built to last several lifetimes.