Freud wrote, “Denken ist Probearbeit.”  In translation: thinking is rehearsal.  For me, this remains one of his most brilliant but overlooked insights. Thought allows us to test possibilities before we act, to rehearse life safely in imagination. and it in some capacity equips us for reality. The difficulty begins when rehearsal never ends. A useful thought is one we can act on or exit. An un-exitable thought is a trap, and for someone already dealing with anxiety or depression, it can become counter productive. What is striking is that Freud never developed this idea further. May be because his work turned relentlessly to the past, whereas rehearsal is a function that belongs to the future.