Quote 1
"Dorian Gray is my dearest friend," he said. "He has a simple and a beautiful nature. Your aunt was quite right in what she said of him. Don't spoil him. Don't try to influence him. Your influence would be bad. The world is wide, and has many marvellous people in it. Don't take away from me the one person who gives to my art whatever charm it possesses: my life as an artist depends on him. Mind, Harry, I trust you." He spoke very slowly, and the words seemed wrung out of him almost against his will.
"What nonsense you talk!" said Lord Henry, smiling, and taking Hallward by the arm, he almost led him into the house. (1.24-25)
And the battle begins. Basil, sadly, is fully aware of what Henry is capable of – he's worried from the very beginning that Henry will turn his young friend from good to evil.
Quote 2
"You know we poor artists have to show ourselves in society from time to time, just to remind the public that we are not savages. With an evening coat and a white tie, as you told me once, anybody, even a stock-broker, can gain a reputation for being civilized." (1.17)
Here, Basil self-deprecatingly admits that even artists have to give in to the demands of society at times – they (who usually inhabit their own creative worlds) have to pretend to be "civilized" on occasion.
Quote 3
"An artist should create beautiful things, but should put nothing of his own life into them. We live in an age when men treat art as if it were meant to be a form of autobiography. We have lost the abstract sense of beauty." (1.21)
Basil highlights exactly what's wrong with the contemporary art scene as he sees it. He thinks that art should be about beauty, not the artist's ego.