Arcana Coelestia #5582
5582. 'Turn back, buy a little food for us' means that, so as to have life, they should acquire the good of spiritual truth. This is clear from the meaning of 'buying' as acquiring and making one's own, dealt with in 4397, 5374, 5397, 5406, 5410, 5426; and from the meaning of 'food' as the good of truth, dealt with in 5340, 5342. Here the good of spiritual truth is meant, because this kind of good is the subject in what follows. That the purpose was for them to have life follows from this.
Arcana Coelestia #5410
5410. 'To buy grain from Egypt' means to make the good of truth its own through factual knowledge. This is clear from the meaning of 'buying' as making one's own, dealt with in 4397, 5374, 5406; from the meaning of 'grain' as the good of truth, dealt with in 5295; and from the meaning of 'Egypt' as factual knowledge, dealt with above in 5402.