Sterilize the Mason jar being used by placing it in boiling water for approximately 10 minutes, or by placing it on the rack in the oven at about 250 degrees for 15 minutes.
Pour all of the ingredients in a Mason jar.
Place a new lid on the jar, and screw it in place firmly with a ring.
Shake the jar vigorously for about 1 minute.
Put the jar in a cool dark place for five weeks.
Shake the jar daily to ensure the milk thistle seeds do not float to the top, and get fully infused with the alcohol and water.
At the end of the designated number of weeks, strain the milk thistle away from the liquid through a fine mesh strainer - keeping the liquid. If you do not have a fine mesh strainer, use a small colander and/or line a colander with several coffee filters to decrease the size of the openings.