Occultism
The student of the occult, you know and understand the uses of the many ingredient and natural resources that hold mystical properties. In order to 'do' magic, you use those things to effect changes on the world around you. Occultists often have a home or workplace, full of readily available preparations, including premixed ingredients and ready to use toolkits. The area itself is also often covered in markings, runes, and treatments that make improvements to the place.
For example:
Holy symbols plated with inherited silver (from melted down jewellry) that are large, heavy, and correctly shaped for use as a mace.
Garlic, holly, and wolfsbane mixed into the potpourri, so that most people can't smell it at first.
Guides to runes, many of which have already been used, being carved into the underside of the desk or painted on the walls but under the wallpaper.
Three specific types of incense that can be burned together in order to hypnotise those that inhale it without having first built up an immunity.
And so on...