They will listen with both ears to what is said by the men just a step or two ahead of them, who stand nearest to them, and within arm's reach. A guide ceases to be of any use when he strides so far ahead as to be hidden by the curvature of the earth.
Is any knowledge worthless? Try to think of an example.
Doubt is the beginning, not the end, of wisdom.
A superstition is a premature explanation that overstays its time.
Ignorance may find a truth on its doorstep that erudition vainly seeks in the stars.
A man's own addition to what he learns is cement to bind an otherwise loose heap of stones into a structure of unity, strength, and use.