In order to understand the true purpose of a moisturizer, we need to know that the essential, primary purpose of our human skin is to receive light. Here’s the process . . .
Electro-magnetic radiation from our sun carries, among other things, photons which are literally packets of information (intelligence) in the form of light. These waves hit the surface of the earth and are translated into thermodynamic energy.
Plants receive and use this EM (electro-magnetic energy - or light) via organelles called plastids. Some of the more familiar plastids are chlorophyll and other pigments. Of course, this is called photosynthesis. This massive, ongoing EM solar event gives plants life but also is the cause of all secondary metabolites created by plants. Other names for secondary metabolites are food and medicine.
In precisely the same way, our human skin is a complex organ that, in combination with the interstitium (a separate organ that is a network of fluid-filled connective tissues throughout the body, including just below the skin) also receives these EM light packages. This is also photosynthesis.
This is important to understand. Plants are not the only life-form on the planet that engage in photosynthesis. Photosynthesis is the principal human biological activity for receiving energy and biologic coding (in the form of electro-magnetic waves) for the healthy functioning of the life-processes of our body. Humans eat light via the skin.
This process of establishing and maintaining the life force via light absorbed by the skin must now be followed by protecting this life force. This is the secondary purpose of our human skin - to serve as an important protective barrier. For it is assailed daily by pollution and environmental stressors, unnatural man-made electro-magnetic frequencies, excess UV exposure and a vast assortment of non-native microbes and pathogens.
So, the most important purpose of a moisturizer would be to support these two processes: eating light and then protecting what that energy source has brought forth. However, these days, there is a third and very important requirement of a highly functional moisturizer, which is to reduce inflammation
That’s it. A real, properly formulated moisturizer will support the functioning of the skin with a minimum of inflammation and maximum of proper nourishment. This in turn brings forth the hallmarks of what we call beautiful skin; radiant (full of light), soft (hydrated with biological lipids), firm (a bounty of healthy fluids in the matrix of the interstitium) and smooth (resisting chronological pressures).