Be patient, therefore, brethren, until the coming of the Lord.  Behold, the farmer waits for the precious produce of the soil, being patient about it, until it gets the early and late rains.  You too be patient; strengthen your hearts, for the coming of the Lord is at hand.

James is asking us for something we do not give often.  Patience.  Look for what he is asking patience to be applied.  

He says, "Be patient... until the coming of the Lord."

Apparently, some of the people in James' church were not being patient about Jesus' second coming.  People thought He came once, and that was it.  The modern philosophy equivalent of this idea would say "God is dead".  Sure, He was here, but He will not come back to help.  James recognizes that this mentality is no good.

The illustration points to a farmer who understands that it takes two rains to make the crops grow.  The early rain gets the crop growing.  Then he has to be patient through the heat - the summer - the drought.  But the second rain comes, and completes the crop growth process.

Many people think Christ's first coming was all there is, while it is the second coming that completes the crop.

Be patient, therefore, brethren, until the coming of the Lord. (and our completion)