This quote essentially emphasizes the importance of recognizing and appreciating the value or merit in something or someone before it becomes widely acknowledged or popular. It suggests that the praise of those who only commend once everyone else does, is meaningless or lost, as it lacks originality and authenticity.

The first part, "Be thou the first true merit to befriend," encourages us to be the first to identify and support genuine talent or worthiness. It’s about having the courage to back something or someone when no one else does, based on your own judgment and understanding.

The second part, "his praise is lost who stays till all commend," criticizes those who only jump on the bandwagon after others have validated the merit. Their praise is seen as insincere or unimportant because it lacks the foresight and courage to support before it became a trend.

Applying this idea in today’s world, we can see its relevance in various fields like art, music, fashion, even in technology or startups. Often, the most significant rewards go to those who can spot the ‘next big thing’ before it becomes mainstream. It’s about being a trendsetter, not a trend follower.

In terms of personal development, it encourages us to trust our own judgment, to have the courage to stand by our beliefs even when they’re not popular or widely accepted. It also encourages us to be genuine in our praise and recognition, not just following the crowd. This authenticity can lead to stronger relationships, better decision-making skills, and a greater sense of self-worth.