"The soul becomes dyed with the color of its thoughts." — Marcus Aurelius
Interestingly, the same metaphor can also apply to leather. If a dyed material (such as blue denim) comes into constant contact with leather which is not regularly cleaned and protected, the dye can transfer to the leather finish and be absorbed by it. This is most noticeable on cream and light-coloured leather. Once the stain is there, it is difficult to remove. In effect, the two pigments have become one, and it is impossible to remove the foreign dye without partially removing the original finish.
An example of this is a job which I completed recently for a client whose taupe-coloured leather armchair recliner had a distinctive pink tinge to the lumbar support and inside back cushion. The pink was the result of dye transfer from a non-colourfast, scarlet-coloured scatter cushion which had been used to provide additional lumbar support. Unfortunately, this stain was unable to be removed by cleaning because the colour had penetrated deep into the pigmented leather finish.