farther, further

Farther or farther means at a greater distance, or to a greater distance or extent, literally or figuratively--
His house is farther away than ours.
There is a rest stop a bit farther down the road.
We can't drive farther than a hundred miles unless we stop for gas first.
Look no farther! Here is a wonderful bargain!
He was right to speak his mind, but he went farther than he should have.

Further or further means additional or more--
No further remarks will be necessary.
Take no further notice of him.
No further nonsense will be tolerated.
Look no further! We found it.

Further also means to advance, or to help the progress of a project or a cause--
He spent his energy attempting to further the cause of compulsory public education.
He claims this treaty will help to further cement our friendship, but we have doubts.

Now that you know that, you can say--
"In an attempt to further his education, he went farther than necessary--he read a set of encyclopedias."