The Sandals enable the magician to "travel on the firmament of Nu." The Sandal-strap is the Ankh which represents the mode of going, going being the essential faculty of every god. This strap, whose form is that of the Rosy Cross, forms a link between the material apparatus of his going and his feet; that is to say, the formula of the Rosy Cross enables a man to go - or, in other words, endows him with Godhead.
The Altar is the foundation of the operation. Its characteristic is stability; also it represents Yesod as supporting the Ruach; that is to say, the means of the Formative World (Ruach = Yetsirah) through which it is proposed to work. The Altar and the sacrifice might also as well have been attributed to Tipareth. This would, in fact, be actually better in the case of certain types of operation, such as invocations of the Holy Guardian Angel, for in this case the human heart is the foundation of the work.
The Perfumes pertain to Yesod as forming a link between earth and heaven. This link is material virtue of the substance of the incense, and spiritual by virtue of their action through the olfactory sense upon the consciousness.
The Vision of the Machinery of the Universe