The Five Principles of Taijiquan

as taught by Benjamin Lo

Body upright

Relax

Beautiful Lady's Hand

Turn Waist

Separate Weight

Each of the five is easy to do in isolation. The "sixth principle" would be - Maintain all these, simultaneously.

Prof. Cheng Man-ch'ing

This photograph of the Master illustrates all 5 principles at once. As he performs yun shou (Cloud Hands), his body is upright, he is relaxed, maintaining his hands as Beautiful Lady's Hand, he's controlling the motion by turning his waist, and his weight is  separated (majority to his left).

[Photo from R. W. Smith; 1967]