"Husband and wife are invisible" = "It is difficult to get married" = "There is no single horoscope for marriage".
*Intangible:
Leave no trace. "Historical Records, Volume 117, Biography of Sima Xiangru": "Those who are enlightened have foresight before they are born, while those who are wise avoid danger by being invisible." ?
Abstract and not tangible. For example: "After the hit-and-run car accident, he suffered invisible torture in terms of conscience and morality.
”