How do I evaluate the left-hand side of this binary expression?

```
Expression<Func<Person, bool>> expr = (x) => x.Birthday.AddMinutes(1) > DateTime.UtcNow;

```

If I call 

```
System.Linq.Expressions.Expression.Lambda(expr.Left).Compile().DynamicInvoke() 

```

I get the error message "variable 'x' of type '...' referenced from scope '', but it is not defined"

To be clear, I want to get the value of x.Birthday.AddMinutes(1) which is a InstanceMethodCallExpressionN