Let us imagine we see two fountains with basins which fill with water.

I can find no simile more appropriate than water by which to explain spiritual things.

[…] These two basins are filled in different ways; the one with water from a distance flowing into it through many pipes and waterworks, while the other basin is built near the source of the spring itself and fills quite noiselessly.

If the fountain is plentiful, like the one we speak of, after the basin is full the water overflows in a great stream which flows continually. No machinery is needed here, nor does the water run through aqueducts.

Such is the difference between the two kinds of prayer. The water running through the aqueducts resembles sensible devotion, which is obtained by meditation.

We gain it by our thoughts, by meditating on created things, and by the labour of our minds. In short, it is the result of our endeavours, and so makes the commotion I spoke of, while profiting the soul.

The other fountain, like divine consolations, receives the water from the source itself, which signifies God.

As usual, when His Majesty wills to bestow on us any supernatural favours, we experience the greatest peace, calm, and sweetness in the inmost depths of our being. I know neither where nor how.

This joy is not, like earthly happiness, at once felt by the heart; after gradually filling it to the brim, the delight overflows throughout all the mansions and faculties, until at last it reaches the body.

Therefore, I say it arises from God and ends in ourselves, for whoever experiences it will find that the whole physical part of our nature shares in this delight and sweetness.

While writing this I have been thinking that the verse dilatasti cor meum, “Thou hast dilated my heart” (Ps. 118:32), declares that the heart is dilated.

This joy does not appear to me to originate in the heart, but in some more interior part and, as it were, in the depths of our being. I think this must be the centre of the soul, as I have since learnt and will explain later on.

Teresa of Avila (1515-1582): Interior Castle 4, 2, 3-5.