Air is, of course, invisible. But air is far from nothing. Air has mass...in fact it is comprised of 9 gases. Interestingly, the largest single gas is not oxygen, which we need to support life. The largest gas within air is nitrogen...about 78% of air is nitrogen and only about 20% of air is oxygen. So why did God put nitrogen in the mix if we don't need it to breathe? It turns out that oxygen is very flammable and reactive while nitrogen subdues reaction and inhibits the tendency of oxygen to combust. Without nitrogen we would truly live in a world on fire, as any spark or excess heat source might cause a roaring inferno. Our designer knows both what we need to live and what is needed to protect us. Air is a great invisible servant.
Genesis 1:6 Then God said, "Let there be a space between the waters, to separate the waters of the heavens from the waters of the earth." 7 And that is what happened. God made this space to separate the waters of the earth from the waters of the heavens. 8 God called the space "sky."