What was Big Willy Shakes going for?
Hamlet's not sure whom he can trust. Can you blame him? His uncle murdered his dad and married his mom. He doesn't know who knows either. There's a whole lot of lies and deceit going around. Luckily, his buddy Horatio is also hanging around. Hamlet knows Horatio is loyal and trustworthy.
But Hamlet goes further than that. He not only trusts Horatio, he praises his very nature. Hamlet thinks that men shouldn't be ruled by their hearts only. Sure, it's great to be passionate about stuff. But a guy who is always only passionate is dangerous. Hamlet likes a guy who is logical and thoughtful like Horatio—you know, to help keep things in check.
In fact, he even goes as far as to say that he'll give his heart to those types. Hamlet thinks that quality is worth showing someone his heart of heart, or heart's core. And show and tell he does. Horatio's the only person in the play Hamlet really trusts with any info. He doesn't even let his girlfriend in on the plan.
Hold on a sec. Isn't it "heart of hearts"? Where's the "s" on the phrase?
For Hamlet, nope. He's actually talking about the heart of his heart, or the center of it. Ogres might be like onions, but humans are like artichokes. The tenderest part of an artichoke is in its core. And that's where the "heart" of something is. So Hamlet's saying that the core of his heart is reserved for men who are just like Horatio—levelheaded and loyal.