Why can't I create a callback for the List Find method in Moq?

I created an extension method that lets me treat a List as DbSet for testing purposes (actually, I found this idea in another question here on stack overflow, and it's been fairly useful). Coded as follows:

    public static DbSet<T> AsDbSet<T>(this List<T> sourceList) where T : class
    {
        var queryable = sourceList.AsQueryable();

        var mockDbSet = new Mock<DbSet<T>>();
        mockDbSet.As<IQueryable<T>>().Setup(m => m.Provider).Returns(queryable.Provider);
        mockDbSet.As<IQueryable<T>>().Setup(m => m.Expression).Returns(queryable.Expression);
        mockDbSet.As<IQueryable<T>>().Setup(m => m.ElementType).Returns(queryable.ElementType);
        mockDbSet.As<IQueryable<T>>().Setup(m => m.GetEnumerator()).Returns(queryable.GetEnumerator());
        mockDbSet.Setup(d => d.Add(It.IsAny<T>())).Callback<T>(sourceList.Add);
        mockDbSet.Setup(d => d.Find(It.IsAny<object[]>())).Callback(sourceList.Find);
        return mockDbSet.Object;
    }

I had been using Add for awhile, and that works perfectly. However, when I try to add the callback for Find, I get a compiler error saying that it can't convert a method group to an action. Why is sourceList.Add an Action, but sourceList.Find is a method group?

I'll admit I'm not particularly familiar with C# delegates, so it's likely I'm missing something very obvious. Thanks in advance.