Ralph Waldo Emerson Quote

Ralph Waldo Emerson once stated, "Unless you try to do something beyond what you have already mastered, you will never grow." I've read the statement over and over in my head and I can't seem to agree with him because of my literal comprehension of the quote. If you have been able to master something in the first place, don't you have to grow from somewhere to get there? Personally, I have yet to master a particular thing in my hobbies and sports. Yet, I still feel as I am growing in those activities. For example track; I excel in the 100 meter sprint and I've been given a natural gift for it yet I haven't mastered it like Usain Bolt or Tyson Gay. Though I still feel as I am honestly growing as an athlete in the event. I also have a passion for photography
A coach can master football plays and his team can become undefeated, but he can extend and grow the game of football by creating new plays. See now that is real growth and Emerson was right about that if that is what he meant by it. When I first read the quote that was my initial interpretation of it, but when I review statements like that I personally interpret it in a logical way. Never being able to grow unless you try to do something beyond what you have already mastered seems illogical to me. I mean, if you have mastered something don't you have to grow and attain knowledge you were blind of before? That is why I believe he wrote it incorrectly. When I read the word "never" I instantly contradicted his opinion. I mean, if I never grew even after mastering something, did I really master it? You see, Emerson's opinion could be right or significantly wrong. It all depends if you read it like I did, or if you read it with more open thought. That's what makes it a bad quote to me. It makes you over think what he's trying to say to the point that you can be agreeing, or in my case, disagreeing with a completely different statement. Although he can make sense in a way, all in all