Here's one of the most simple practical examples that proves to me cats are conscious. When my cat sleeps in my bed occasionally I accidetanlly kick or bump into her in the dark. Instead of fleeing, hissing or attacking me she lets out a very unique earnest meow that clearly means 'hey I'm here' and she goes back to sleep like nothing happened. She clearly understands my motivation wasn't to harm her. She clearly understands we share a common motivation of sleeping in the comfy bed. She clearly understands a concept of the future where she lets me know her position and expects me not to accidentally bother her again. If I continue to bother he she will simply get up and move just far enough away to avoid further trouble.