It is always difficult to analyze a famous quote when taken out of context, and this quote by Abraham Lincoln is certainly no exception.
Lincoln's quote begins by addressing friendship; Lincoln values friendship, but also recognizes the importance of being your own person. So how can friendship as a weak point relate to strength? Friends are a valuable resource. Perhaps the key to understanding this quote lies in yet another pearl of wisdom from our sixteenth president. In another quote, Lincoln says:
"I am thankful to all those who said 'no' to me. It's because of them I did it myself."
With this thought in mind, friendship may seem like a detriment to building personal fortitude and strength; going alone and depending solely on one's own merits builds immense character.
If friendship was a person's weakest point, that person would probably not have very many friends to support and encourage them; he or she would have to be incredibly independent and strong.
As a self-made man, Lincoln would certainly appreciate the importance of self-reliance.