Another Trick

When painting a light source, the brightest light an artist has is pure white pigment.  But an even brighter light can be implied. 

 An example from Rembrandt shows how.  In this painting, a detail of a picture illustrating a bible story, the woman is holding a candle - the main light source illuminating the painting - but it is hidden behind her hand.  Touches of pure white paint are applied near the source of light, thus implying that the candle flame is even brighter.

I applied this lesson to a painting I am currently working on.  The reflection of the sun on the water is pure white paint, implying that the sun, beyond the edge of the picture, is brighter than its reflection.

Try it sometime.