It's commonly quoted (probably inaccurately) that Einstein never bothered remembering his home phone number because it could easily be looked up in a phone book

It's commonly quoted (probably inaccurately) that Einstein never bothered remembering his home phone number because it could easily be looked up in a phone book. The brain very regularly expands outside itself to think or remember, almost like subcontracting. Smartphones have just made them a one-stop shop for all our external thinking now.