What's this guy saying?

0The following is a colloquial speech, in which a guy makes a comment about Buddha, after Buddha discovers that people get sick and must die.02br
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01i00It's not plausible to think that growing up as an intelligent youth he wouldn't have known anything about it. But the point is rather to convey the tremendous impact that coming face to face with these fundamental facts of human existence 01b00has and must have upon us02b00.02i02br
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00Now, the first sentence is talking about the Buddha, how he supposedly hadn't known anything about it before seeing it firsthand in his venture. The second sentence follows upon it, by saying that in fact, and in strict sense it's not that he hadn't known anything about it, but the idea is to convey the tremendous impact of coming face to face with this. The part where I'm curious about is the part where it says "(the impact) has and must have upon us." Now, it's making reference to us, the audience, or the common folk in today's society. So the speech makes a sort of a transition, from talking about the Buddha to talking about us. The issue is where exactly the transition takes place in thought. We may not have had a tremendous impact when we came face to face with the fundamental facts of human existence; that's a very assuming statement that doesn't really have any grounds. So it may be talking in relation to the Buddha, which, makes more sense because of the first sentence. The part "must have upon us" is nodoubt a talking in relation to us. Here again the speech, or the guy, makes an assumption that we must feel the tremendous impact. Actually, it's not really saying that, but it's saying if we were in Buddha's shoes, then he would have felt the tremendous impact. So in summary, the guy meant that Buddha felt the tremendous impact (by the 'has' part), and we would feel the same if we were in Buddha's shoes (by the 'must have upon us' part), am I correct? What other interpretation would you get if you heard that? I realize I explained myself in sort of a confusing way because I'm still confused about the sentence, as to what it really means, but hope it's enough for you to help.0-