In the question 'What is Prayer?' the object of the querist is to learn the meaning of the term _Prayer_. The Interrogative _what_ refers to the genus of Existence, as in the question 'What is Man?' not to the word _Prayer_, which is the subject of the query. It is equivalent to 'What is [that thing which is named] Prayer?' In those languages where a variety of gender is prevalent, this reference of the Interrogative is more conspicuously marked. A Latin writer would say '_Quid_ est Oratio*?' A Frenchman, 'Qu' est-ce que la Prière?' These questions, in a complete form, would run thus; 'Quid est [id quod dicitur] Oratio?' 'Qu' est-ce que [l'on appelle] la Prière?' On the same principle, and in the same sense, a Gaelic writer must say, 'Ciod e urnuigh?' the Interrogative Ciod e referring not to urnuigh but to some higher genus. The expression, when completed, is 'Ciod e [sin de 'n goirear] urnuigh?'
Is there then no case in which the Interrogative may follow the gender of the subject? If the subject of the query be expressed, as it often is, by _a general term, limited in its signification_ by a noun, adjective, relative clause, &c; the reference of the Interrogative is often, though not always not necessarily, made to _that term_ in its general acceptation, and consequently be 'What is the Lord's Prayer?' Here the subject of the query is not _Prayer_, but an individual of that species, denoted by the term _prayer_ limited in its signification by another noun. The Interrogative _what_ may refer, as in the former examples, to the genus of Existence; or it may refer to the species _Prayer_, of which the subject of the query is an individual. That is, I may be understood to ask either 'What is that _thing_ which is called the Lord's Prayer?' or 'What is that _prayer_ which is called the Lord's Prayer?' A Latin writer would say, in the former sense, 'Quid est Oratio Dominica+?' in the latter sense, 'Quaenam est Oratio Dominica?' The former of these expressions is resolvable into 'Quid est [id quod dicitur] Oratio Dominica?' the latter into 'Quaenam [oratio] est Oratio Dominica?' The same diversity of expression would be used in French: 'Qu' est-ce que l'Oraison Dominicale?' and 'Quelle est l'Oraison Dominicale?' The former resolvable into 'Qu' est-ce que [l'on appelle] l'Oraison Dominicale? the latter into 'Quelle [oraison] est l'Oraison Dominicale? So also in Gaelic, 'Ciod e Urnuigh an Tighearna?' equivalent to 'Ciod e [sin de'n goirear] Urnuigh an Tighearna?' or, which will occur oftener, 'Ciod i Urnuigh an Tighearna?' equivalent to 'Ciod i [an urnuigh sin de 'n goirear] Urnuigh an Tighearna?'