Connectivity

Touch any water anywhere, and you are touching all the water on the planet. Aside from water locked in tanks and bottles and closed geologic formations, of course. But when I touch the water in the stream in my backyard, that water is touching every lake and river and ocean on the planet. Although they are all touching, the water bodies of the world are separated by chemistry (salinity, pH), temperature (ice), pressure (water vapor), and saturation of different media (our bodies, plants, soil, air). These barriers prevent aquatic organisms from swimming freely everywhere. For a microbe to swim from my finger, down my creek, through the ocean, up the Angara River, and into Lake Baikal, it would take a lot of time and success in surmounting a few of these barriers. But the same surface tension I can touch stretches all around the world to Lake Baikal and every other water body not separated by a physical barrier.

Air is another substance that is connected--again unless it is locked in tanks and bottles and impermeable areas. I'm breathing the same air as someone in Beijing--although luckily for me, the concentration of pollutants in the air varies spatially, and various processes remove pollutants from the air. But the substance is the same everywhere.

Life is also connected to all other life. The energy, nutrients, and water that pass through all life is shared and recycled over and over again, so that a molecule in one being eventually will travel through all other beings.

John Muir said it best:

"When we try to pick out anything by itself, we find it hitched to everything else in the Universe."

Hike up a headwater stream that is dry, and think about the moist soil in the streambed that connects all the water molecules in it to all the ones that stretch all the way down to the ocean, and then up to all the other headwater streams in the world. They are all connected. Pick any two places on Earth, and there is a line of water molecules connecting them.