How could his spiritual brethren have been so blind?

Then we lived in the dimension beyond this material plane with our spiritual brothers and sisters.

A gaseous intelligence from inside a star could well be a spiritual brother; Kim knew that.

He was also extremely formal in front of others, not giving away that he and Mac were both spiritual brothers and old friends.

That privilege was reserved for Agrippa, his coeval and spiritual brother.

They were spiritual brothers and the best of friends.

Given this setting, it may be Arbeo who is addressed in the dedication as a "spiritual brother."

Instead, he sent a letter of gratitude that seemed a moving farewell to his spiritual brethren.

He wasn't a spiritual brother to the clerk aboard the receiving ship after all.

His essay is an effort to reach out and touch a spiritual brother.