The need to think abstractly makes programming difficult, especially for normal people. To make programming more concrete I propose to represent programs as data structures reifying their execution. Programming shifts from editing textual abstractions to direct inspection and manipulation of concrete executions. Reified execution also helps ground abstraction through a new testing mechanism: _interventions_. An intervention tests and overrides behavior at a specific point within a reified execution, replacing hand-coded tests and mocks. Intervention points are stable because programs are edited structurally, not textually. Interventions also provide _scaffolding_ that assists program development through refactoring-like steps of _gradual abstraction_.