Can you see the air?

Last night Trinity was sleeping in my bed, as well as Samuel, and she was fussing that she was "scared" in my room. We discussed how she shouldn't be scared because dad and mom are there and God is there.
"No, God is far away."
God lives in your heart, honey.
"No, God lives in heaven."
Yes, but God's Spirit is here with us, He is in the room with us.
"I don't see him."
No, you can't see God, but He is here. Just like your brains. Do you have a brain?
"No."
Yes, you do! Your brain is in your head, but can you see it?
"No."
Do you have blood?
"Yes."
Can you see your blood?
"No." (she is getting it now, by the grin on her face.)
God is like that, He is there, but you can't see Him.
Like air! You can't see air, can you?
"I can see the air in Hope-Anne's room!"

Oh, dear. That is true. Her hamsters bedding floats around the room sometimes, lol.