Ecclesiastes 4:8; Ecclesiastes 4:16; Ecclesiastes 12:12
There is one alone, and there is not a second; yea, he hath neither child nor brother: yet is there no end of all his labour; neither is his eye satisfied with riches; neither saith he, For whom do I labour, and bereave my soul of good? This is also vanity, yea, it is a sore travail.
There is no end of all the people, even of all that have been before them: they also that come after shall not rejoice in him. Surely this also is vanity and vexation of spirit.
And further, by these, my son, be admonished : of making many books there is no end; and much study is a weariness of the flesh.