Rinse soybeans well.
Place in a large bowl with 6 cups water.
Soak 8 to 10 hours until soybeans have doubled in size.
Drain well and discard water.
Place half the beans in blender with 3 cups water.
Blend to a fine paste.
Empty blender.
Repeat with remaining soybeans and 3 more cups of water.
Spread 3 layers of cheesecloth over a large saucepan.
Pour soybean paste into cheesecloth.
Bring corners of cheesecloth together and twist, squeezing milk from soybean paste.
Add remaining 6 cups water to paste.
Squeeze cheesecloth again, adding it to soybean milk in large saucepan.
Discard paste and cheesecloth.
Bring soy milk almost to a boil over medium heat, stirring frequently.
Remove from heat.