weak and unable...

This is from a great old(er) book called A Mother's Heart, by Jean Fleming:

"Henry Venn, an eighteenth century pastor, once wrote to a concerned widow about her son who had a greater appetite for pleasure than for God. Venn said that this painful experience should teach the mother about ...your own weakness and inability to give a single ray of light, or to excite the faintest conviction of sin, or to communicate the least particle of spiritual good, to one who is dearer to you than life. How ought this to take away every proud thought of our own sufficiency, and to keep us earnest, importunate suppliants at the door of the Almighty's mercy and free grace."