The implied logic is "This person was Great, and said X, therefore X is Good". It is only fair to point out this can be used to support the almost polar opposite of the quote you chose.

I mean, people should make up their own minds, instead of being swayed by authority, no?

And the Einstein quote wasn't aimed at 'any' race - it was aimed specifically at the Chinese. The implication being that being supplanted by the Chinese is worse than if by some other race.

The implied logic you name is actually your presumed logic. I certainly don't read that logic into every time someone uses a quote.

Quotes can be used to show that past generations have said similar or relevant things

Quotes can be used because they were interestingly or eloquently phrased

Quotes can evoke someone's connection to a subject without relying on an appeal to authority.

Probably the last thing I'd assume is that someone is seriously positing the quality of an argument based on who said it. Such a logic would probably be expressed explicitly if it was key to the message.

> Such a logic would probably be expressed explicitly if it was key to the message.

Not if you don't want the audience to critically examine it. Commercials don't say "product X will give you a happy family" - they just happen to show a happy family using product X.

The subject is Einstein. The Darwin quote also fit perfectly to humanity being "just one big tribe", and both quotes expand that to sentient beings. That was my point, not "yeah, Darwin also said something similar and is also considered important, so it's double true".

I'd be happy for you to critically examine both, and express any issues you have with the actual content of the quotes. But you're not doing that, you're doing anything but that. That's not my intention, that's your choice.

> The implied logic is "This person was Great, and said X, therefore X is Good"

It's supposed by you, not automatically implied by quoting someone; that just implies "this is an eloquent way to phrase something I agree with, and this is the source".