how is this quote an example of racism - our past didn't matter, in the present you were invisible and you had no claim in the future.

As a slave you are invisible:stripped of all identity. You no longer have a past or a future. Your only reality is indentured servitude-you are a non-person. She was robbed of her childhood, stolen like an object and carried away. When she walks down the street, she can tell that nobody sees her. Her person-hood is irrelevant to the white faces around her. Finally, she has no idea what the future holds for her, and she has next to no means or volition with which to influence that future. In short, she feels that slavery makes a slave into an object.