This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
We poor gardeners, among the many other frailties and weaknesses of human nature, have been denounced by some of the critics for having been all more or less touched by a yellow, scarlet, and blue mania. There may be some truth in the accusation, but there is certainly a great amount of nonsense written on this head. That these colours are indispensable, I think all will admit; and to such as require a really good yellow, I would advise them to try the golden Prince of Orange Calceolaria. I bedded it last season, and found it most superb in spite of the drought of summer: when Violas had not a bloom on them, it was literally a mass of flower, and continued to be so until the frost killed it. I used it last year, and it was the admiration of all who saw it; in fact, every one exclaimed, "What a splendid yellow!" It is very dwarf and compact, quite shrubby in its habit, a free grower, and has a large quantity of small trusses just raised above the foliage, and is of a most rich brilliant yellow.
I had the centre of some round beds last summer that you could not have pricked the point of your walking-stick into without touching the flowers in the whole bed, it was such a mass of bloom.