Note: This is a General Reference question, easily answered by any dictionary worthy of the name.
The full quote is:
Look around you. Wherever you live, whatever circle of society you are part of, you will notice that the vast majority of people lives in the world without. Those who are more enlightened, however, are intensely involved with the world within. They realize—as you will, too—that the world within creates the world without.
Here, the words within and without are being used as modifiers following the nouns they modify and respectively meaning inside and outside.
So “the world within” simply means “the inside world”, and “the world without” simply means “the outside world”.
A dictionary would have explained this sense of without. The OED gives this use as the first of all of them for without. Here is a sampling of relevant senses:
I. Outside, in various senses: opp. to within adv. Now only literary and somewhat arch.
- On the outside or outer surface (of a material thing); externally.
- a. Outside (or out of) the place mentioned or implied; esp. outside the house or room; out of doors.
b. transf. Outside of a class, body, or community; not in the number or membership; in an alien or foreign community. those (that are) without = ‘outsiders’. Now only in echoes of 1 Cor. v. 12.
- fig. and gen. Outside of the inward being, soul, or mind; with regard to external actions or circumstances; in relation to others or to something other than the self; sometimes, in outward appearance as opposed to inward reality; outwardly.
- Used absol. by ellipsis of obj., in opposition to within (or in) prep., where it has the appearance of an adv.