Henry David Thoreau wrote in chapter 2 of Waldon:.
Time is but a stream I go a-fishing in. I drink at it; but while I drink I see the sandy bottom and detect how shallow it is. It's thin current slides away, but eternity remains. I would drink deeper; fish in the sky, whose bottom are pebbly with stars. I cannot count one. I know not the first letter of the alphabet. I have always been regretting that I was not as wise as the day I was born. The intellect is a cleaver; it discerns and rifts its way into then secret of things. I do not wish to be any more busy with my hands than is necessary. My head is hands and feet. I feel all my best faculties concentrated in it. My instincts tell me my head is an organ for burrowing, as some creatures use their snout and fore-paws, and with it I will mine and burrow my way through these hills. I think that the richest vein is somewhere hereabouts; so by the divining rod and thin rising vapors I judge; and here I will begin to mine. .
In this passage, Thoreau is trying to Understand the complexities of our lives, as well as that of the time we spend here. He begins by comparing time to a stream, an ever-flowing endless body of water, yet he is still able to see the bottom. In saying this, I gather he is comparing his life span (the distance to the bottom) to the ever-flowing body of time. He is telling us our life is but a short period in the stream of time. It is important to understand that we are not as significant as we would like to believe. Thoreau believes the only way to cut through this insignificance is to use our intellect like a "cleaver".
Cut through the all of the social mores and beliefs that have jaded our view on this wonderful world in which we live. To cut through our own faults and fears and discover the vein of truth that is within us all. He teaches us not to bother with unnecessary busy work, and focus on the more important things in our lives.