I think the word is mind? But if not, what are the choices?
In my opinion, it is true because McCandless got ready for the trip by packing elementary things, opposed to the things we pack nowadays where technology absorbs much of our attention and time.
Through this quote, the author implies that today's society has limited our sense of freedom and adventure due to the increased use of technological devices which have become the new way to enjoy and be encased in a virtual world at the same time. In the past, children enjoyed more freedom and used to engage in more fun and adventurous games, rather than virtual ones as it happens at present time.
