We are happy when we see a garden bursting with color, texture and shape of many different types of flowering plants. Try to imagine every flower with the same color and shape. The same petal, the same height and the same smell! Boring!!
Think of us as flowers and our garden is Earth. It would be like Heaven on Earth for every human being to be in the same garden, gloriously bursting with our own beautiful color and dancing in the same wind, as the same Sun warms us all and the same soil sustains us and the same rain fills our petals with drops of life. I found a few quotes from the Baha'i Writings that describe this garden.
"The world of humanity is like a garden and the various races are the flowers.The very fact that there is difference and variety lends a charm to the garden. If all [the flowers] were of the same colour the effect would be monotonous and depressing....." Baha'i Writings
"The garden which is pleasing to the eye and which makes the heart glad, is the garden in which are growing side by side flowers of every hue, form and perfume, and the joyous contrast of colour is what makes for charm and beauty." Baha'i Writings
"May the rain of the Divine Mercy and the warmth of the Sun of Truth make your gardens fruitful, so that many beautiful flowers of exquisite fragrance and love may blossom in abundance." Baha'i Writings