What does "essence" mean? And how can it be inside of you? Even when you consume something (a chocolate cake, a car, or even a relationship) you have only consumed the form. It is like the shell of a nut without the kernel, and that is why forms can never, ever satisfy. What you are really searching for is the kernel, the essence, the interior sense of fullness and satisfaction.
But as long as you are looking "out there" you won't find that essence. It is "in here," already inside of you. And it is by manifesting your Spirit that you gain access to that hidden essence. Only by manifestation do you bring it out and put it to work in your life.