6730. 'To wash at the river' means worship involving the use of falsity. This is clear from the meaning of 'washing' as purification from what is understood spiritually by filth, dealt with in 3147, worship consequently being meant since worship takes place for the sake of purification; and from the meaning of 'the river', in this case the river of Egypt, as falsity, dealt with in 6693.

The internal meaning of “blood” is a little tricky. In most cases, blood is linked with Divine Truth and it’s relationship with the Lord. But in some cases, especially when discussing the first half of Genesis, the Works of Swedenborg link blood to a state of caring, or love to the neighbor. No absolute explanation is offered for this, but it’s worth noting that blood takes a number of forms in the body – it sometimes carries nutrients and oxygen, sometimes waste products, and sometimes nutrients and carbon dioxide. So it’s not unreasonable for blood to have different meanings in different contexts.