When it comes to understanding the theory of evolution, a modern textbook will teach you more than reading Darwin would. In fact it's absurd to suggest otherwise. You can't understand the theory unless you know it, and there have been a some major advances since Darwin.
Even for understanding the basics a decent pop science book would probably be easier to read and directed at a more appropriate level for a beginner. And it would be based on more complete information, having the advantage of access to the work done since Darwin.
In fact it is true in general that to understand how anything works now it is far better to study it now, than it is to know the origins. The only people I've seen argue otherwise are creationists.
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