Most cats love being stroked by their owners because the sensation feels similar to what they felt when they were being groomed by their mother as kittens. But cats also have a built-in survival mechanism that kicks in to prevent them from getting too comfortable. This duality can easily be observed as stress starts to build up during petting: sudden silence, stiffening, and sweeping of the tail are all signs that the stress is becoming too much. If you ignore these warnings, at some point your cat will feel too vulnerable and lash out as a result.