Rendering a model in Backbone??

gistfile1.js

render: function(layout) {
var view = layout(this);
	var themeId = this.options.themeId;
	
	/* THIS WORKS, BUT WHY DO I NEED TO LOOP THE COLLECTION?!?! */
        this.collection.each(function(theme) {
		if (theme.id == themeId) {
			console.log('theme: ', theme);
			view.insert(new ThemeEditor.Views.PreviewContent({
				model: theme
			}));
		}
	});
	
	
	/* THIS DOESN'T WORK */
        var theme = this.collection.get(themeId);
	view.insert(new ThemeEditor.Views.PreviewContent({
		model: this.collection.get(themeId)
	}));
		
return view.render();
},