Sarek and Director in “Unfinished Business”

Sarek

I have created in her a being of exquisite logic to rival the best of our species.

An accomplishment you have achieved not once but twice. Your ward, Michael, and your son, Spock.

Sarek

What has my son to do with this situation? He has not yet begun his studies at the Science Academy.

Upon completion, he will apply to the Vulcan Expeditionary Group, and then there will be not one but two non-Vulcans in its ranks.

Sarek

Spock is Half-Vulcan.

Another of your experiments. The integration of humans into our culture is an admirable goal, but it must be titrated. In honor of your position and reputation I will accept one of your not-quite-Vulcans.

Sarek

You ask me to make an impossible choice.

Your reaction to this is quite illogical and suggests a conclusion based on emotion.