Julius Caesar says, "The sun rises in the east" but he points to the west. What does that mean?

Decius, Caska, and Cinna, three of the several conspirators, have met at Brutus’ house to plan the assassination. As dawn approaches they must depart, and noting morning is near, disagree as to where sunrise will occur. Caska states:

Cask.
You shall confesse, that you are both deceiu'd:
737: Heere, as I point my Sword, the Sunne arises,
738: Which is a great way growing on the South,
739: Weighing the youthfull Season of the yeare.
740: Some two moneths hence, vp higher toward the North
741: He first presents his fire, and the high East
742: Stands as the Capitoll, directly heere.
743:
Bru.
Giue me your hands all ouer, one by one.

“Youthful season of the year” refers to it being mid-march; the sun rises more northerly until the summer solstice. “Sunne” and “Sonne” are used interchangeably throughout the play; Caska’s words may be an allegory, as he may be pointing his sword to Brutus or Cassius and commenting on their ascendancy, as both are described in various scenes as “sons of Rome,” implying that they will in two months time “stand as the Capitol.” Compare this with Caesar’s soliloquy as being as “constant as the northern star.” Note also Caska uses his sword first on Caesar.