sense; reason(the power of the mind to think, form opinions and judgements etc. • Only man has reason – animals have not); understanding; intelligence(у человека); mind; nous; brain; wits; consciousness; brainpower(Andrey Truhachev); senses(usually with my, his, her etc.; a person's normal, sane state of mind • He must have taken leave of his senses; When he came to his senses, he was lying in a hospital bed)
human brain(the world is too complex to be understood by the human brain – мир слишком сложен, для того, чтобы его можно было понять человеческим разумом Юрий Павленко); cogito(Alex_Odeychuk)