Burden of Expectation

I hoist the sack you've filled for me, up high upon my waiting back my knees they buckle 'neath the weight, but I must move, no time to wait These needs of yours that now are mine, must make it to the finish line, where you will wait to judge my pace, if I should stumble in this race The load that's laden on my back, begins to creak and then to crack, the sorry sack must surely burst, by God, I swear I'll reach you first Should one iota fall to ground, though there be not a single sound, I'd turn at once, back to the start, for I would know, deep in my heart A burden that I cannot best, would be if I'm to fail your test so on I walk beneath this heft, for this is all for me, that's left