Some philosophers say that our life is meaningless because it has a prescribed end. This is a strange assertion: is a movie rendered meaningless because of its finiteness? Some things acquire a meaning precisely because they are finite: consider academic studies, for instance. It would seem that meaningfulness does not depend upon matters temporary.
We all share the belief that we derive meaning from external sources. Something bigger than us - and outside us - bestows meaning upon our lives: God, the State, a social institution, an historical cause.
Yet, this belief is misplaced and mistaken. If such an external source of meaning were to depend upon us for its definition (hence, for its meaning) - how could we derive meaning from it? A cyclical argument ensues. We can never derive meaning from that whose very meaning (or definition) is dependent on us. The defined cannot define the definer. To use the defined as part of its own definition (by the vice of its inclusion in the definer) is the very definition of a tautology, the gravest of logical fallacies.
On the other hand: if such an external source of meaning were NOT dependent on us for its definition or meaning - again it would have been of no use in our quest for meaning and definition. That which is absolutely independent of us - is absolutely free of any interaction with us because such an interaction would inevitably have constituted a part of its definition or meaning. And that, which is devoid of any interaction with us - cannot be known to us. We know about something by interacting with it. The very exchange of information - through the senses - is an interaction.
Thus, either we serve as part of the definition or the meaning of...