For placing a mid line loop that is strong, secure; and easily untied.  Best if both legs of line are loaded and just not the loop, and not loop and 1 leg of line.  Loop can be loaded or unloaded, doesn't affect strength.  Line inside of loop can be damaged, cut through, or 2 separate lines, using the ButterFly as a Bend.  So it can be an eye to secure to, or to isolate a weak part of line out of the system as well; also as a 2 way stopper in the bight.

Making a ButterFly Knot
	Take a Round Turn + on palm as shown.  To look like 3 turns from the top side (2 on bottom).  Then take the (L)-Left strand and place it between the (C)-Center and (R)-Right strands, to go to look like next picture thumbnail.
	Following the Previous direction, your knot should look like this.  Then, we want to take the present (L)-Left strand (that was previously (C)-Center)) and pass it over both the other strands, so it ends up on (R)-Right.
	Pinch the strand you just moved in between fingers as shown, so as to hook, twist, pull the pinched strand underneath the other 2 strands.
	This is just as you are drawing your hand thru the 2 turns with the piece of line you pinched between fingers above; just keep pulling.
	Till it stands like this.  (A) + (B) are the 'wings of the ButterFly Knot as you Inspect the lacing
	This is simply the flip side (A) + (B) are still the wings, and the true symmetry of the ButterFly Knot can be seen.  Symmetrical knots are easier to inspect, as you kinda can check 1 end against the other, and the knot has a balanced look to the eye.
Making ButterFly w/Larger Loop
	To make a larger loop, simply make the center turn bigger, for this is the one that eventually makes up the loop.  after running around in a circle and ending up center again!
	As the Left turn moves Center, the Center (Yellow) becomes Left.
	Then the Yellow jumps right, and passes thru the other 2 turns; where it will become the loop, after starting from Center; so Center turn determines the size of the loop.
	ButterFly with larger loop, that started as Center; still has it's clean, symmetrical 'wings' connecting to the mainline.  Inspection/ instant identification/familiarity i think is an important knotting step; to follow the standard TDS (Tie, Dress, Set) format with 'I' (Inspect).  Simple and symmetrical aids in easy identification, as here.
ButterFly as a Bend
	The knot is so strong, the loop so secure, to Bend/ tie 2 lines together; place on hand the same as above examples.  Make the intersection of the 2 lines to be joined the center turn (lines going around in the same direction).
	Follow the pattern, and the lines are secured strongly.   The ButterFly as a Bend; to join 2 lines:  Simplicity, Strength and Security, also; easy to inspect and untie.
	Double and Triple ButterFlies